20664

Appears in sequences

• Expansion of Product_{m>=1} (1 - m*q^m)^9.at n=12A022669
• Open 3-dimensional ball numbers (version 3): a(n) is the number of integer points (i,j,k) contained in an open ball of diameter n, centered at (1/2,1/2,0).at n=34A053595
• Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 19 (most significant digit on right).at n=24A061972
• a(n) = 12*n*(n-1).at n=42A064200
• 9 times octagonal numbers: a(n) = 9*n*(3*n-2).at n=28A064201
• At stage 1, start with a unit equilateral equiangular triangle. At each successive stage add 3*(n-1) new triangles around outside with edge-to-edge contacts. Sequence gives number of triangles (regardless of size) at n-th stage.at n=35A064412
• Numbers k such that k^6 + 1091 is prime.at n=13A066386
• Triangle: let f(t) = 1 + t + t^2 and g(t) = t + t^2, expansion of p(t) = f(t)*exp(x*g(t)).at n=51A137391
• a(n) = 16*n^2 - 2*n.at n=35A158058
• Number of n X n symmetric 0..6 arrays with rows, considered as 7-ary numbers, in strictly increasing order.at n=2A162131
• Number of nX2 1..4 arrays containing at least one of each value, all equal values connected, rows considered as a single number in nondecreasing order, and columns considered as a single number in decreasing order.at n=9A166838
• Table, read by antidiagonals, in which the n-th row comprises A214206(n) 0 followed by a second-order recursive series G in which each product G(i)*G(i+1) lies in the same row of A001477 (interpreted as a square array).at n=28A182431
• Sum of the parts of all partitions of n-1 plus the sum of the emergent parts of the partitions of n.at n=21A182707
• Triangle of coefficients of polynomials u(n,x) jointly generated with A208766; see the Formula section.at n=51A208765
• Indices of primes in the tribonacci-like sequence, A214825.at n=28A230016
• Number of hands of n points in Spanish dominoes.at n=16A258064
• Number of hands of n points in Spanish dominoes.at n=38A258064
• Numbers n such that there exists an x!=n that makes {x,x,n} an amicable multiset.at n=3A259303
• Numbers that belong to at least one amicable multiset.at n=36A259307
• Numbers n such that sigma(sigma(n))/sigma(n) > sigma(sigma(m))/sigma(m) for all m < n.at n=23A289124