19740

Appears in sequences

• Theta series of D_7 lattice.at n=9A008429
• Number of ways of writing n as a sum of 7 squares.at n=18A008451
• Fibonacci sequence beginning 0, 20.at n=16A022354
• Shifts left 2 places under "BHJ" (reversible, identity, labeled) transform.at n=8A032083
• Numbers k such that the decimal part of k^(1/6) starts with a 'nine digits' anagram.at n=6A034281
• Numbers k such that the sum of unitary divisors of k^2 is a square.at n=13A064498
• Numbers k such that k^6 + 1091 is prime.at n=11A066386
• Numbers k such that the sign of core(k)-phi(k) is not equal to 2*mu(k)^2-1, where core(k) is the squarefree part of k.at n=36A070237
• a(n) = sigma_3(n) - sigma_1(n).at n=25A092348
• a(n) =(A001359[n]^2-1)/2.at n=18A117849
• Triangle of coefficients of q in e.g.f. that satisfies: A(x,q) = exp( q*x*A(q*x,q) ), read by rows of [n*(n-1)/2 + 1] terms in row n for n>=0.at n=55A126265
• Refines A075197(n): number of partitions of n balls of n colors. The refinement has shape A000041(n).at n=35A130273
• a(n) is the smallest number k larger than a(n-1) such that n*d(k)*sopf(k)=sigma(k), where d is the number of divisors (A000005) and sopf the sum of prime factors without repetition (A008472).at n=20A134382
• G.f. satisfies: 3*A(x) = 5*x + x^2 - 2*Series_Reversion( A(x) ).at n=5A139087
• Number of vertices of degree 1 in all non-crossing connected graphs on n points on a circle.at n=5A143021
• 3 times 13-gonal (or tridecagonal) numbers: a(n) = 3*n*(11*n - 9)/2.at n=35A153875
• Numbers such that each digit from 0 to 9 appears at least 7 times in the digits of their divisors.at n=25A175507
• Number of strings of numbers x(i=1..6) in 0..n with sum i^3*x(i)^2 equal to 216*n^2.at n=40A184307
• Triangle T(n,k), read by rows, given by (0, 2, 3, 4, 6, 6, 9, 8, 12, 10, 15, ...) DELTA (1, 0, 1, 0, 1, 0, 1, 0, 1, 0, ...) where DELTA is the operator defined in A084938.at n=41A185285
• Integers that do not have a partition into a sum of an odd square and two (not necessarily distinct) triangular numbers.at n=37A191764