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 A296178 G.f. A(x) satisfies: [x^n] A(x)^(2^n) = 2^(n^2+n) for n>=0. 1
 1, 2, 10, 316, 49286, 29159004, 64306390660, 545236870010872, 18158564638452610374, 2398983772627848027521708, 1262702849939184484481521481260, 2653266051323723630100943807028591432, 22278972285891863226312849051379722700141980, 747923506928218814067091395575400399337895942101656, 100409109325359541267889114151049368121212293075871991443656 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Paul D. Hanna, Table of n, a(n) for n = 0..80 EXAMPLE G.f.: A(x) = 1 + 2*x + 10*x^2 + 316*x^3 + 49286*x^4 + 29159004*x^5 + 64306390660*x^6 + 545236870010872*x^7 + 18158564638452610374*x^8 + 2398983772627848027521708*x^9 + 1262702849939184484481521481260*x^10 +... such that the coefficient of x^n in A(x)^(2^n) equals 2^(n*(n+1)) for n>=0. ILLUSTRATION OF THE DEFINITION. The table of coefficients of x^n in A(x)^(2^n) begins: n=0: [1, 2, 10, 316, 49286, 29159004, 64306390660, ...]; n=1: [1, 4, 24, 672, 99936, 58521472, 128730502912, ...]; n=2: [1, 8, 64, 1536, 205824, 117874688, 257934426112, ...]; n=3: [1, 16, 192, 4096, 440320, 239239168, 517783552000, ...]; n=4: [1, 32, 640, 14336, 1048576, 494141440, 1043408617472, ...]; n=5: [1, 64, 2304, 69632, 3424256, 1073741824, 2119989985280, ...]; n=6: [1, 128, 8704, 434176, 21069824, 2906652672, 4398046511104, ...]; n=7: [1, 256, 33792, 3096576, 229048320, 18765316096, 10095488401408, 72057594037927936, ...]; ... in which the main diagonal equals 2^(n^2+n): [1, 4, 64, 4096, 1048576, 1073741824, 4398046511104, ..., 4^(n*(n+1)/2), ...]. RELATED SERIES. log(A(x)) = 2*x + 16*x^2/2 + 896*x^3/3 + 194560*x^4/4 + 145293312*x^5/5 + 385486422016*x^6/6 + 3815756479332352*x^7/7 + 145259790155527487488*x^8/8 + 21590527069867423236620288*x^9/9 + 12626980518625294860075743051776*x^10/10 +... MATHEMATICA terms = 15; A[x_] = Sum[a[n]*x^n, {n, 0, terms-1}]; c[n_] := Coefficient[A[x]^(2^n), x, n] == 2^(n^2+n) // Solve // First; Do[A[x_] = (A[x] /. c[n]) + O[x]^terms, {n, 0, terms-1}]; CoefficientList[A[x], x] (* Jean-François Alcover, Jan 14 2018 *) PROG (PARI) {a(n) = my(A=[1]); for(m=1, n, A = concat(A, 0); V = Vec( Ser(A)^(2^m) ); A[m+1] = 2^(m^2) - V[m+1]/2^m; ); A[n+1]} for(n=0, 20, print1(a(n), ", ")) CROSSREFS Sequence in context: A079278 A275611 A015178 * A206152 A261007 A013034 Adjacent sequences: A296175 A296176 A296177 * A296179 A296180 A296181 KEYWORD nonn AUTHOR Paul D. Hanna, Jan 05 2018 STATUS approved

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Last modified November 28 22:51 EST 2022. Contains 358421 sequences. (Running on oeis4.)