A158827 The 4th iteration of x*C(x) where C(x) is the Catalan function (A000108).

1, 4, 20, 110, 640, 3870, 24084, 153306, 993978, 6544242, 43652340, 294469974, 2006018748, 13784115468, 95444016984, 665407010349, 4667570034444, 32922870719664, 233389493503968, 1662048903052380, 11885333877149532

Offset

1,2

Links

Table of n, a(n) for n=1..21.

Elżbieta Liszewska, Wojciech Młotkowski, Some relatives of the Catalan sequence, arXiv:1907.10725 [math.CO], 2019.

Formula

Series reversion of 1 -4*x +12*x^2 -30*x^3 +64*x^4 -118*x^5 +188*x^6 -258*x^7 +302*x^8 -298*x^9 +244*x^10 -162*x^11 +84*x^12 -32*x^13 +8*x^14 -x^15. - R. J. Mathar, Aug 30 2021

Prog

(PARI) {a(n)=local(F=serreverse(x-x^2+O(x^(n+1))), G=x); for(i=1, 4, G=subst(F, x, G)); polcoeff(G, n)}

Crossrefs

Cf. A158825, A158826, A158828, A158829.

Sequence in context: A271932 A153295 A006770 * A263854 A026156 A025183

Adjacent sequences: A158824 A158825 A158826 * A158828 A158829 A158830

Keyword

nonn

Author

Paul D. Hanna, Mar 28 2009

Status

approved