19680

Appears in sequences

• Generalized tangent numbers d_(n,2).at n=16A000176
• Theta series of direct sum of 2 copies of f.c.c. lattice.at n=22A008663
• Theta series of lattice D3 tensor D3* (dimension 9, det. 262144, min. norm 6).at n=24A033694
• Number of partitions of n with equal nonzero number of parts congruent to each of 0 and 1 (mod 3).at n=52A035537
• Numbers whose base-3 representation contains exactly one 0 and no 1's.at n=36A044970
• Expansion of e.g.f. (1-2x)(1-x)/(1-4x+2x^2).at n=5A052659
• Number of primitive (aperiodic) palindromes using a maximum of three different symbols.at n=16A056459
• Number of primitive (period n) periodic palindromes using a maximum of three different symbols.at n=16A056494
• The sequence lambda(3,n), where lambda is defined in A055203. Number of ways of placing n identifiable positive intervals with a total of exactly three starting and/or finishing points.at n=9A058809
• Numbers k such that sigma (x) = k has exactly 12 solutions.at n=22A060676
• a(n) = 12*n*(n-1).at n=41A064200
• Numbers n such that n-th cyclotomic polynomial evaluated at phi(n) is a prime number.at n=34A070525
• Maximal cycle lengths in a certain class of one-dimensional cellular automata.at n=48A085590
• a(n) = 2*a(n-1) - a(n-4) + a(n-5) with a(-1)=a(0)=a(1)=1, a(2)=2, a(3)=4, a(4)=7.at n=17A108758
• Number of regions formed inside square by diagonals and the segments joining the vertices to the points dividing the sides into n equal length segments.at n=33A108914
• Expansion of -2*x*(-8-12*x+9*x^2) / ( (x-1)*(3*x-1)*(3*x+1)*(1+x) ).at n=8A120468
• Triangle related to super-Catalan numbers (or little Schroeder numbers).at n=49A130743
• a(n) = A000244(n) - A010684(n).at n=9A141317
• Strongly refactorable numbers: numbers n such that if n is divisible by d, it is divisible by the number of divisors of d.at n=25A141586
• Positive integers n such that n^2 = (x^4 - y^4)*(z^4 - t^4) where the pairs of integers (x,y) and (z,t) are not proportional.at n=19A147854