56700

Appears in sequences

• a(n) = n!*(n-1)!/2^(n-1).at n=6A006472
• Triangle of coefficients from fractional iteration of e^x - 1.at n=20A008826
• Expansion of e.g.f.: sech(log(x+1)-arcsinh(x))=1-3/4!*x^4+30/5!*x^5-180/6!*x^6+945/7!*x^7...at n=9A013281
• Numbers k such that the square of d(k) (number of divisors) divides k.at n=22A046754
• Denominator of coefficient of Pi^n in Ramanujan-like series for Zeta[4n+3].at n=1A057867
• McKay-Thompson series of class 24I for Monster.at n=34A058579
• Numbers k such that A074037(k) = A002034(k).at n=37A074055
• Triangle of coefficients, read by rows, where the n-th row forms the polynomial P(n,x) = {Sum_{k=1..n} 1/(k+x)}*{Product_{k=1..n} (k+x)}.at n=41A074246
• Ordered m for which m = k^3*a*b*(a^4 - b^4) determine (unique) solution triples(k,a,b), where k=1,2,3,... and (a,b) are coprime pairs, not both odd (i.e., of opposite parity).at n=30A081779
• Numbers k such that the three second-degree cyclotomic polynomials x^2 + 1, x^2 - x + 1 and x^2 + x + 1 are simultaneously prime when evaluated at x=k.at n=31A087277
• Triangle read by rows in which row n gives coefficients of polynomial R_n(y) that satisfies R_n(1/3) = 9^n, where R_n(y) forms the initial (n+1) terms of g.f. A097191(y)^(n+1).at n=18A097190
• Triangle, read by rows, where T(n,k) = n!/(k!*(n-4*k)!*4^k) for n>=4*k>=0.at n=20A118933
• Even refactorable numbers n such that the number r of odd divisors and the number s of even divisors are both even divisors of n and n is the first number for which the triple (r,s,t) occurs, where t is the number of divisors of n.at n=33A120356
• Triangle read by rows: T(n,k) is the number of ternary trees with n edges and having k leaves (i.e., vertices of degree 0; n>=0, k>=1). A ternary tree is a rooted tree in which each vertex has at most three children and each child of a vertex is designated as its left or middle or right child.at n=27A120429
• Triangle of coefficients of (x+1)*(x+3)*(x+6)*...*(x+n(n+1)/2).at n=27A128813
• Irregular triangle read by rows: T(n, k) = f(n, A113474(n-1) - k), where f(n, k) = (n-1)!/2^k if (n-1)!/2^k is an integer, otherwise f(n, k) = 0.at n=42A129915
• McKay-Thompson series of class 24I for the Monster group with a(0) = 2.at n=34A138688
• Denominators of the coefficients of the polynomials 1/Sum_{n>=1} x^(n-1)/((2*n)!/n!) = 2*exp(-x/4)*sqrt(x)/ (sqrt(Pi)*erf(sqrt(x)/2)).at n=4A154242
• Number of nonoverlapping placements of one 1 X 1 square and one 2 X 2 square on an n X n board.at n=15A173963
• n-th derivative of arctan(x) at x = 1, n >= 4.at n=7A177146