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 A274738 E.g.f. satisfies: A(x) = exp( x * Integral A(x) dx ). 2
 1, 2, 20, 480, 21200, 1495040, 154090560, 21851648000, 4080788691200, 970763776819200, 286589492301132800, 102814798964090470400, 44054406432402362880000, 22221550008574568038400000, 13033785372897433673984000000, 8796017673121387398310133760000, 6767531687276918248610686607360000, 5888477519317946191613742861516800000, 5753199370152454677482310592627507200000, 6271818135933778813784553455691078041600000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Since the e.g.f. is an even function, this sequence consists of the coefficients of only the even powers of x. LINKS Paul D. Hanna, Table of n, a(n) for n = 0..200 FORMULA E.g.f. A(x) equals the logarithmic derivative of the e.g.f. of A274739. a(n) ~ c * n!^2 * d^n / sqrt(n), where d = 3.0991310195... and c = 0.8742487... . - Vaclav Kotesovec, Jul 06 2016 EXAMPLE E.g.f.: A(x) = 1 + 2*x^2/2! + 20*x^4/4! + 480*x^6/6! + 21200*x^8/8! + 1495040*x^10/10! + 154090560*x^12/12! + 21851648000*x^14/14! + 4080788691200*x^16/16! +... where A(x) = exp( x * Integral A(x) dx ). PROG (PARI) {a(n) = my(A=1); for(i=0, n, A = exp( x*intformal( A +x*O(x^(2*n)) ) ) ); (2*n)!*polcoeff(A, 2*n)} for(n=0, 20, print1(a(n), ", ")) CROSSREFS Cf. A274739. Sequence in context: A210901 A274572 A292396 * A012816 A012340 A279839 Adjacent sequences:  A274735 A274736 A274737 * A274739 A274740 A274741 KEYWORD nonn AUTHOR Paul D. Hanna, Jul 05 2016 STATUS approved

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Last modified December 2 05:01 EST 2021. Contains 349437 sequences. (Running on oeis4.)