21675

Appears in sequences

• Number of Barlow packings with group P3(bar)m1(O) that repeat after 2n layers.at n=13A011952
• Number of n X n matrices over GF(4) with rank 1.at n=3A060869
• a(1) = 3, a(n) = a(n-1) + 4*(a(n-1)-floor(a(n-1)^(1/3))^3).at n=22A096297
• Numbers n that are the hypotenuse of exactly 12 distinct integer-sided right triangles, i.e., n^2 can be written as a sum of two squares in 12 ways.at n=7A097226
• One seventh of the sum of the first n primes, when an integer.at n=33A112272
• Base-2 logarithm of (n-th even superperfect number divided by 2^n).at n=24A134712
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (0, 1, 0), (1, 0, 1), (1, 1, -1), (1, 1, 0)}.at n=7A151158
• Odd numbers k such that A166100((k-1)/2)/k is not an integer.at n=24A166102
• 3*h^2, where h is an odd integer not divisible by 3.at n=28A229852
• Coordination sequence for (2,4,8) tiling of hyperbolic plane.at n=25A265063
• Positions of 3's in A264977; positions of 6's in A277330.at n=41A277713
• Numbers that are the sum of three squares in arithmetic progression.at n=34A292313
• G.f.: 1 + Sum_{n>=1} a(n)*x^n/(1 - x^n) = Product_{n>=1} (1 + x^n)^n.at n=19A300276
• Number of compositions (ordered partitions) of n into octagonal pyramidal numbers (A002414).at n=56A322856
• G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 + x^4 + x^5 * A(x)^3.at n=22A346735
• Numbers k for which A327500(k) <> A351946(k).at n=42A351947
• Array read by ascending antidiagonals: A(n, k) = (k^n - 1)^2/(k - 1), with k >= 2.at n=23A379587