cp's OEIS Frontend

A337577 O.g.f. A(x) satisfies: [x^n] exp( n^2*(n-1) * x/A(x) ) = 0 for n > 0.

%I A337577 #7 Sep 03 2020 02:10:07
%S A337577 1,2,22,1616,286700,90914400,44673096808,31286975152640,
%T A337577 29552473932597968,36189841095064294016,55768927589536556250016,
%U A337577 105641404186261853184309888,241363180288689801902138103872,654744988347389437898766097063424
%N A337577 O.g.f. A(x) satisfies: [x^n] exp( n^2*(n-1) * x/A(x) ) = 0 for n > 0.
%C A337577 It is remarkable that this sequence consists entirely of integers.
%F A337577 Given o.g.f. A(x), define B(x) = A(x*B(x)), then B(x) is the o.g.f. of A337578 and satisfies [x^n] exp( n*(n+1)^2*x ) / B(x)^(n+1) = 0 for n>0.
%e A337577 O.g.f.: A(x) = 1 + 2*x + 22*x^2 + 1616*x^3 + 286700*x^4 + 90914400*x^5 + 44673096808*x^6 + 31286975152640*x^7 + 29552473932597968*x^8 + ...
%e A337577 ILLUSTRATION OF DEFINITION.
%e A337577 The table of coefficients of x^k/k! in exp( n*(n-1)^2 * x/A(x) ) begins:
%e A337577 n=0: [1, 0, 0, 0, 0, 0, 0, ...];
%e A337577 n=1: [1, 0, 0, 0, 0, 0, 0, ...];
%e A337577 n=2: [1, 4, 0, -560, -154880, -137342976, -261610747904, ...];
%e A337577 n=3: [1, 18, 252, 0, -822960, -670328352, -1230620630976, ...];
%e A337577 n=4: [1, 48, 2112, 77760, 0, -2077949952, -3628874151936, ...];
%e A337577 n=5: [1, 100, 9600, 869200, 68473600, 0, -8724419840000, ...];
%e A337577 n=6: [1, 180, 31680, 5423760, 890714880, 130187520000, 0, ...];
%e A337577 n=7: [1, 294, 85260, 24343200, 6817260240, 1850897137824, 453595543361856, 0, ...]; ...
%e A337577 in which the main diagonal is all zeros after the initial term, illustrating that [x^n] exp( n*(n-1)^2 * x/A(x) ) = 0 for n>0.
%e A337577 RELATED SERIES.
%e A337577 Define B(x) = A(x*B(x)), which begins
%e A337577 B(x) = 1 + 2*x + 26*x^2 + 1756*x^3 + 301140*x^4 + 94035272*x^5 + 45829458720*x^6 + 31938032357440*x^7 + ... + A337578(n)*x^n + ...
%e A337577 then the table of coefficients of x^k/k! in exp( n*(n+1)^2*x ) / B(x)^(n+1) begins:
%e A337577 n=0: [1, -2, -44, -9960, -7049664, -11131647360, -32715852151680, ...];
%e A337577 n=1: [1, 0, -96, -20480, -14247072, -22395261696, -65687348011520, ...];
%e A337577 n=2: [1, 12, 0, -34176, -22928112, -34905615552, -100977330265344, ...];
%e A337577 n=3: [1, 40, 1408, 0, -34275648, -51114811392, -142803802229760, ...];
%e A337577 n=4: [1, 90, 7860, 613000, 0, -71887626240, -199085724252800, ...];
%e A337577 n=5: [1, 168, 27936, 4535040, 663960096, 0, -269327647065600, ...];
%e A337577 n=6: [1, 280, 78064, 21598080, 5858601168, 1443397611264, 0, ...];
%e A337577 n=7: [1, 432, 186240, 80041984, 34200321408, 14371727121408, 5514496883009536, 0, ...]; ...
%e A337577 in which the main diagonal is all zeros after the initial term, illustrating that [x^n] exp( n*(n+1)^2*x ) / B(x)^(n+1) = 0 for n>0.
%e A337577 Also note that B(x) = (1/x)*Series_Reversion( x/A(x) ) and A(x) = B(x/A(x)).
%o A337577 (PARI) {a(n) = my(A=[1]); for(i=1, n, A=concat(A, 0); m=#A; A[m] = Vec( exp(m^2*(m-1)*x/Ser(A) ))[m+1]/(m^2*(m-1)) );A[n+1]}
%o A337577 for(n=0, 20, print1(a(n), ", "))
%Y A337577 Cf. A337578, A337575, A337457.
%K A337577 nonn
%O A337577 0,2
%A A337577 _Paul D. Hanna_, Sep 02 2020