A290581 Column 1 of triangle A290580.

1, 20, 364, 7028, 148752, 3471192, 89097664, 2503362488, 76575071488, 2536513162508, 90532686154752, 3465845396598540, 141726054915248128, 6167370619705004144, 284635248765764878336, 13889365886508877963184, 714612366728939248091136, 38667882915659893417754820, 2195406208657284278474506240, 130509259754593318496376665060, 8107405596523654695095077175296, 525358015896796804145274761270600

Offset: 1

Author

Paul D. Hanna, Aug 07 2017

Keywords

• nonn

Comments

a(n) = A290580(n+2,1) for n>=1.

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 1..75

Crossrefs

Cf. A290580, A291214.

Programs

PARI

/* As column 1 of triangle A290580 */
{ A290580(n,k) = my(W=1,E=1, S=x,C=1,D=1); for(i=0,n,
S = intformal(C*D +x*O(x^n)) ;
C = 1 - intformal(S*D) ; D = 1 - m*intformal(S*C) ;
E = subst( (1 + S)/C,m,1-m) ) ;
for(i=0,n, W = subst(E,x,x*W));
n!*polcoeff(polcoeff(W, n,x), k,m) }
for(n=1,25, print1( A290580(n+2,1), ", "))

Formula

a(n) ~ c * n^(n+2), where c = (exp(5) - 4*exp(3) - exp(1))/16 = 4.0845455988354304513775733719295... - Vaclav Kotesovec, Aug 21 2017