63840

Appears in sequences

• Numbers j such that j and 2j are both between a pair of twin primes.at n=17A066388
• Special values of the hypergeometric function 3F1: a(n) = binomial(n,2) * hypergeom([1,-n+1,-n+2],[3],1).at n=6A080996
• Numbers that can be expressed as the difference of the squares of primes in exactly eight distinct ways.at n=10A092004
• Phi(A033631(n)) {phi is the Euler totient function A000010}.at n=28A115620
• Number of ways of placing ceiling(n/2) nonattacking queens on an n X n Mobius chessboard.at n=9A137279
• a(n) is the number of partial bijections (or subpermutations) of an n-element set without fixed points (also called partial derangements).at n=7A144085
• T(n,k) is the number of partial bijections (or subpermutations) of an n-element set with exactly k fixed points.at n=28A144088
• a(n) = 18522*n - 10248.at n=3A157731
• G.f. satisfies: A(x) = G(x/A(x))^2 and G(x)^2 = A(x*G(x)^2) where G(x) = Sum_{n>=0} C(2*n,n)*C(2*n+2,n+1)/(n+2)*x^n is the g.f. of A172392.at n=10A172391
• n such that n = product of 3 consecutive even numbers and n+-1 are primes.at n=4A174384
• Numbers with prime factorization pqrst^5.at n=3A190383
• Number of 4 X n 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=13A207255
• T(n,k) = number of n X k nonnegative integer arrays with new values 0 upwards introduced in row major order and every value unique in its row and column.at n=29A211709
• T(n,k) = number of n X k nonnegative integer arrays with new values 0 upwards introduced in row major order and every value unique in its row and column.at n=34A211709
• Triangle read by rows, coefficients of polynomials related to the Springer numbers A001586.at n=40A214554
• Numbers m such that exactly four subsets of {m-1, m, m+1} sum up to a prime number.at n=20A221310
• Triangle read by rows, T(n, k) = 4^k*S_4(n, k) where S_m(n, k) are the Stirling-Frobenius subset numbers of order m; n >= 0, k >= 0.at n=17A225467
• Integer areas A of integer-sided cyclic quadrilaterals such that the circumradius is of prime length.at n=22A230136
• Triangle read by rows: T(n,k) is the number of subpermutations of an n-set whose orbits are each of size at most k, and without fixed points. Equivalently, T(n,k) is the number of partial derangements of an n-set each of whose orbits is of size at most k.at n=35A261762
• Number of nX3 0..2 arrays with no element equal to more than one of its king-move neighbors, with the exception of exactly two elements, and with new values introduced in order 0 sequentially upwards.at n=5A281535