Sequences

a(n) = n!*(3*n^2 - 15*n + 10)/6.

a(n) = n!*(3*n^2 - 15*n + 10)/6, n > 4.

a(n) = n!*(4*n^3 - 30*n^2 + 40*n + 3)/24.

a(5) = 5, a(6) = 1170, for n >= 7, a(n) = n!*(4*n^3 - 30*n^2 + 40*n + 3)/24.

a(n) = n!*(n-4)/2.

a(n) = n!*(n-4)/2, n > 4, and a(4) = 4.

Triangle of odd-numbered terms in rows of Pascal's triangle.

Left half of Pascal's triangle.

Right half of Pascal's triangle.

Even-numbered rows of Pascal's triangle.

Odd-numbered rows of Pascal's triangle.

Central column of Losanitsch's triangle A034851.

Primes in which each digit occurs in runs of at least 2.

a(1) = 1; for n >= 2, a(n) = n times the reverse of a(n-1).

Smallest integer not the sum of powers of some earlier terms.

Number of ways to write n! as a product of smaller factorials each greater than 1.

Rows of (Pascal's triangle - Losanitsch's triangle) (n >= 0, k >= 0).

Numbers k such that k! can be written as the product of smaller factorials.

a(n) = product of factorials of digits of a(n-1).

Minimal number of rectangles with integer sides that will form any rectangle with area n.

a(1) = 1; for n>1, a(n) = smallest integer > a(n-1) such that a(n)*a(i)+1 is prime for all 1 <= i <= n-1.

Product of consecutive factorials.

Maximum length of Euclidean algorithm starting with n and any nonnegative i<n.

Numbers k such that k < d(k)^2, where d(k) = A000005(k).

Record values of sigma(n).

Number of digits in n!.

Number of digits in 2^n.

Number of digits in 3^n.

Number of embeddings on the sphere of 2-connected planar graphs with n nodes.

Duplicate of A009490.

Number of different products of partitions of n; number of partitions of n into prime parts (1 included); number of distinct orders of Abelian subgroups of symmetric group S_n.

Number of balanced signed graphs on n unlabeled nodes.

Maximum of different products of partitions of n into distinct parts.

Dropping any digit gives 0, 1 or a composite number.

Dropping any digit gives a prime number.

Number of solutions to a^2 + b^2 + 3*c^2 + 3*d^2 = n.

Hyperperfect numbers: x such that x = 1 + k*(sigma(x)-x-1) for some k > 0.

n-th term of A034897 is an a(n)-hyperperfect number.

Euler transform of powers of 2 [ 2,4,8,16,... ].

a(n) is square mod a(i), i < n; a(n) prime; a(1) = 2.

a(n) is square mod a(i), i < n; a(n) nonsquare; a(1) = 2.

a(i) is a square mod a(j), i <> j; a(n) prime; a(1) = 2.

a(i) is a square mod a(j), i <> j.

Related to sept-factorial numbers A045754.

Numbers whose square contains no loops in its digits (assumes 1, 2, 3, 5, 7 have no loops and 0, 4, 6, 8, 9 do).

Powers of 2 written backwards and sorted.

a(n) in base 10 is a(n-1) in base a(n-1).

One half of octo-factorial numbers.

One third of octo-factorial numbers.

One quarter of octo-factorial numbers.