Sequences

Symmetries in unrooted (1,3) trees on 2n vertices.

Symmetries in planted 3-trees on n+1 vertices.

Symmetries in unrooted 3-trees on n+1 vertices.

Number of symmetries in planted (1,4) trees on 3n-1 vertices.

Symmetries in unrooted (1,4) trees on 3n-1 vertices.

Symmetries in planted 4-trees on n+1 vertices.

Symmetries in unrooted 4-trees on n+1 vertices.

Smallest n-digit prime.

Largest n-digit prime.

Not of form [ e^m ], m >= 1.

Number of iterations until 3n reaches 153 under x goes to sum of cubes of digits map.

Number of iterations until n reaches 1 or 4 under x goes to sum of squares of digits map.

The Wythoff compound sequence AA: a(n) = floor(n*phi^2) - 1, where phi = (1+sqrt(5))/2.

Wythoff AB-numbers: floor(floor(n*phi^2)*phi), where phi = (1+sqrt(5))/2.

Duffinian numbers: composite numbers k relatively prime to sigma(k).

Primes congruent to {3, 5, 6} mod 7.

Inert rational primes in Q(sqrt(-5)).

Primes of the form 3n-1.

Primes congruent to {5, 7} mod 8.

Primes p == +- 3 (mod 8), or, primes p such that 2 is not a square mod p.

Inert rational primes in Q[sqrt(3)].

Primes congruent to 2 or 3 modulo 5.

Inert rational primes in Q(sqrt 7), or, 7 is not a square mod p.

The sequence 2^(1-n)*a(n) is fixed (up to signs) by Stirling2 transform.

Smallest positive integer that is n times its digit sum, or 0 if no such number exists.

Inconsummate numbers in base 10: no number is this multiple of the sum of its digits (in base 10).

Number of classes per genus in quadratic field with discriminant -n.

Number of classes per genus in quadratic field with discriminant -4n+1.

Number of classes per genus in quadratic field with discriminant -4n, -n == 2,3( mod 4).

Number of classes per genus in Q(sqrt -n), n squarefree.

Number of genera of imaginary quadratic field with discriminant -k, k = A003657(n).

Number of genera of imaginary quadratic field with discriminant -k, k = A039957(n).

Number of genera of imaginary quadratic field with discriminant -k, k = A191483(n).

Number of genera of Q(sqrt(-n)), n squarefree.

Discriminants of the known imaginary quadratic fields with 1 class per genus (a finite sequence).

a(n) = 2^n * C(n+1), where C(n) = A000108(n) Catalan numbers.

Class number of binary quadratic forms with fundamental discriminant A003658(n),n>=2.

Class number of real quadratic forms with discriminant 4n+1.

Class number of quadratic forms with discriminant 4n, n == 2,3^( mod 4).

Class number of real quadratic field Q(sqrt f), where f is the n-th squarefree number A005117(n).

Class number of real quadratic field with discriminant 4n+1.

Class number of real quadratic field with discriminant 4n, n == 2,3 ( mod 4).

Class number of real quadratic field with discriminant A003658(n), n >= 2.

Discriminants of quadratic fields whose fundamental unit has norm -1.

Squarefree integers m such that the fundamental unit of Q(sqrt(m)) has norm -1. Also, squarefree integers m such that the Pell equation x^2 - m*y^2 = -1 is soluble.

Discriminants of real quadratic fields with narrow class number 1.

Discriminants of real quadratic fields with unique factorization.

Discriminants of imaginary quadratic fields, negated.

Fundamental discriminants of real quadratic fields; indices of primitive positive Dirichlet L-series.

Shifts left under Stirling2 transform.