21514

Appears in sequences

• a(n) = a(n-1) + a(n-2) + 1, with a(0)=3, a(1)=10.at n=17A022409
• Denominators of continued fraction convergents to sqrt(664).at n=12A042277
• Triangle: a(n,m) = number of permutations of (1,2,...,n) with one or more fixed points in the m first positions.at n=33A061018
• Let M(n) be the n X n matrix m(i,j)=min(i,j) for 1<=i,j<=n then a(n) is the trace of M(n)^(-6).at n=24A114358
• Triangle T, read by rows, formed by a column bisection of triangle A117418: column k of T equals column 2*k of A117418.at n=60A117425
• Number of partitions p of n such that (maximal multiplicity of the parts of p) <= (maximal part of p).at n=38A240311
• Number T(n,k) of occurrences of k in a (signed) displacement set of a permutation of [n]; triangle T(n,k), n>=1, 1-n<=k<=n-1, read by rows.at n=54A306461
• Number T(n,k) of occurrences of k in a (signed) displacement set of a permutation of [n]; triangle T(n,k), n>=1, 1-n<=k<=n-1, read by rows.at n=58A306461
• Number T(n,k) of permutations p of [n] having at least one index i with |p(i)-i| = k; triangle T(n,k), n>=1, 0<=k<=n-1, read by rows.at n=33A306506
• Number of 5-element subsets of [n] whose sum is a triangular number.at n=29A320851
• For 1<=x<=n, 1<=y<=n, write gcd(x,y) = u*x+v*y with u,v minimal; a(n) = n^4*s, where s is the population variance of the values of u^2+v^2.at n=6A345691
• Expansion of Sum_{k>=0} (-2)^k * x^(2*k)/Product_{j=1..k} (1 - j * x).at n=13A353261