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 A295811 G.f. A(x) satisfies: [x^(n-1)] A(x)^(n^2) = 2*n * [x^(n-2)] A(x)^(n^2) for n>=2, with A(0) = 1. 3
 1, 1, 2, 11, 140, 2898, 80844, 2786091, 113184008, 5266198778, 275248731860, 15939117549502, 1012084698990904, 69901132180300132, 5217426460077854712, 418615099531669351443, 35942031310982080239120, 3289533291926922095871546, 319841125714352173292953668, 32937612567848507536114539402, 3582858531960091228861488651864 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Compare g.f. to: [x^(n-1)] G(x)^n = 2 * [x^(n-2)] G(x)^n for n>=2 holds when G(x) = 1/(1-x). LINKS Paul D. Hanna, Table of n, a(n) for n = 0..300 FORMULA a(2^k - 1) is odd for k>=0 and a(n) is even elsewhere (conjecture). a(n) ~ c * d^n * n! / n^3, where d = -4/(LambertW(-2*exp(-2))*(2+LambertW(-2*exp(-2)))) = 6.176554609483480358231680164050876553672889794284... and c = 2.719099850893334482... - Vaclav Kotesovec, Feb 07 2018 EXAMPLE G.f.: A(x) = 1 + x + 2*x^2 + 11*x^3 + 140*x^4 + 2898*x^5 + 80844*x^6 + 2786091*x^7 + 113184008*x^8 + 5266198778*x^9 + 275248731860*x^10 + ... ILLUSTRATION OF THE DEFINITION. The table of coefficients of x^k in A(x)^(n^2) begins: n=1: [1, 1, 2, 11, 140, 2898, 80844, ...]; n=2: [1, 4, 14, 72, 741, 13724, 364546, ...]; n=3: [1, 9, 54, 327, 2826, 42660, 1017720, ...]; n=4: [1, 16, 152, 1216, 10540, 129376, 2559792, ...]; n=5: [1, 25, 350, 3775, 37750, 427480, 6820800, ...]; n=6: [1, 36, 702, 10056, 123165, 1477980, 20712546, ...]; n=7: [1, 49, 1274, 23667, 359856, 4953998, 69355972, ...]; ... in which the main diagonal D0 = [1, 4, 54, 1216, 37750, 1477980, 69355972, 3775816704, ...] and the adjacent diagonal D1 = [1, 9, 152, 3775, 123165, 4953998, 235988544, 12954335103, ...] are related by D0[n-1] = 2*n*D1[n-2] for n>=2. The related sequence D0[n-1]/n^2, n>=1, begins: [1, 1, 6, 76, 1510, 41055, 1415428, 58997136, 2878741134, 160698224230, ...]. PROG (PARI) {a(n) = my(A=[1]); for(m=2, n+1, A=concat(A, 0); V=Vec(Ser(A)^(m^2)); A[#A] = V[#A-1]*2/m - V[#A]/m^2 ); A[n+1]} for(n=0, 20, print1(a(n), ", ")) CROSSREFS Cf. A295766, A088715, A300873. Sequence in context: A077544 A087480 A060059 * A177753 A183609 A113148 Adjacent sequences:  A295808 A295809 A295810 * A295812 A295813 A295814 KEYWORD nonn AUTHOR Paul D. Hanna, Feb 02 2018 STATUS approved

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Last modified May 12 13:46 EDT 2021. Contains 343823 sequences. (Running on oeis4.)