71760

Appears in sequences

• a(n) = floor(n*(n-1)*(n-2)*(n-3)/5).at n=26A011915
• a(n) = A000203(n) * A024916(n).at n=37A143238
• Triangle read by rows: row n gives coefficients of expansion of polynomial p(k,n) in powers of k, defined by p(k, 0) = 1, p(k, 1) = 1+2*k; for n>1, p(k,n) = If[Mod[n, 2] == 0, (1 + 2*k)*p(k, n - 1) + n*Binomial[n + 1, n - 1]*k*(k + 1)*p(k, n - 2), (1 + 2*k)*(1 + 3*(p(k, n - 1) - 1))].at n=27A167883
• Numbers with prime factorization p*q*r*s*t^4 (where p, q, r, s, t are distinct primes).at n=19A190110
• Integer areas A of integer-sided cyclic quadrilaterals such that the circumradius is of prime length.at n=23A230136
• Numbers k such that R_(k+2) + 5*10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=9A256931
• Number of compositions of 5*n-3 into parts 4 and 5.at n=16A369851
• a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4) + a(n-5) with a(1) = a(2) = a(3) = 0, a(4) = 1, and a(5) = 3.at n=21A385142
• a(n) = Sum_{k=0..floor(n/2)} binomial(k,2*(n-2*k)).at n=41A392250