This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A214654 #30 Feb 21 2014 03:30:26 %S A214654 1,1,4,29,307,4288,74511,1550203,37588412,1041217039,32446359005, %T A214654 1123624632224,42814687805649,1780347364682777,80231627759556196, %U A214654 3895332991309376213,202713074683790193475,11256955024502873008864,664444403260495390747071 %N A214654 E.g.f. A(x) satisfies: A'(x) = exp( A(x)*A'(x) ). %C A214654 Compare to the trivial identity: G'(x) = exp(G(x)) when G(x) = -log(1-x). %H A214654 Vaclav Kotesovec, <a href="/A214654/b214654.txt">Table of n, a(n) for n = 1..240</a> %F A214654 E.g.f. A(x) satisfies: %F A214654 (1) A''(x) = A'(x)^3/(1 - A(x)*A'(x)). %F A214654 (2) A(x) = x + Sum_{n>=2} (n-2)^(n-2)*A(x)^n/n!. %F A214654 (3) A'(x) = Sum_{n>=0} (n+1)^(n-1)*A(x)^n/n!. %F A214654 (4) A(x)*A'(x) = Sum_{n>=1} n^(n-1)*A(x)^n/n!. %F A214654 (5) A(x) = Series_Reversion( Integral -x/LambertW(-x) dx ). %F A214654 Let W(x) = Sum_{n>=2} (n-2)^(n-2)*x^n/n!, then e.g.f. A(x) satisfies: %F A214654 (6) A(x) = Series_Reversion(x - W(x)). %F A214654 (7) A(x) = x + Sum_{n>=1} d^(n-1)/dx^(n-1) W(x)^n/n!. %F A214654 (8) A(x) = x*exp( Sum_{n>=1} d^(n-1)/dx^(n-1) W(x)^n/(n!*x) ). %F A214654 a(n) ~ 2^(2*n-3) * n^(n-2) / (exp(n-2) * (1+exp(-2))^(n-3/2)). - _Vaclav Kotesovec_, Feb 17 2014 %F A214654 A(x) = Series_Reversion( -((x^2*(1 + 2*LambertW(-x))) / (4*LambertW(-x)^2)) + 1/4). - _Vaclav Kotesovec_, Feb 21 2014 %e A214654 E.g.f.: A(x) = x + x^2/2! + 4*x^3/3! + 29*x^4/4! + 307*x^5/5! + 4288*x^6/6! +... %e A214654 By definition log(A'(x)) = A(x)*A'(x), where: %e A214654 (3) A'(x) = 1 + x + 4*x^2/2! + 29*x^3/3! + 307*x^4/4! + 4288*x^5/5! +... %e A214654 (4) A(x)*A'(x) = x + 3*x^2/2! + 19*x^3/3! + 185*x^4/4! + 2437*x^5/5! + 40523*x^6/6! + 814355*x^7/7! + 19196769*x^8/8! + 519397829*x^9/9! +... %e A214654 RELATED SERIES: %e A214654 Let W(x) = x^2/2! + x^3/3! + 4*x^4/4! + 27*x^5/5! + 256*x^6/6! + 3125*x^7/7! +...+ (n-2)^(n-2)*x^n/n! +... then %e A214654 (6) A(x) = x + W(A(x)); equivalently, A(x - W(x)) = x. %e A214654 (7) A(x) = x + W(x) + d/dx W(x)^2/2! + d^2/dx^2 W(x)^3/3! + d^3/dx^3 W(x)^4/4! +... %e A214654 (8) log(A(x)/x) = W(x)/x + d/dx W(x)^2/(2!*x) + d^2/dx^2 W(x)^3/(3!*x) + d^3/dx^3 W(x)^4/(4!*x) +... %t A214654 Rest[CoefficientList[InverseSeries[Series[-((x^2*(1 + 2*LambertW[-x])) / (4*LambertW[-x]^2)) + 1/4,{x,0,20}],x],x]*Range[0,20]!] (* _Vaclav Kotesovec_, Feb 21 2014 *) %o A214654 (PARI) {a(n)=local(A=x);for(i=1,n,A=intformal(exp(A*A'+x*O(x^n))));n!*polcoeff(A,n)} %o A214654 for(n=1,25,print1(a(n),", ")) %o A214654 (PARI) {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D} %o A214654 {a(n)=local(A=x,W=sum(m=2,n+1,(m-2)^(m-2)*x^m/m!)+x*O(x^n)); A=x+sum(m=1, n, Dx(m-1, W^m/m!)); n!*polcoeff(A, n)} %o A214654 (PARI) {Dx(n, F)=local(D=F); for(i=1, n, D=deriv(D)); D} %o A214654 {a(n)=local(A=x,W=sum(m=2,n+1,(m-2)^(m-2)*x^m/m!)+x*O(x^n)); A=x*exp(sum(m=1, n, Dx(m-1, W^m/x/m!)+x*O(x^n))); n!*polcoeff(A, n)} %Y A214654 Cf. A210949, A214645. %K A214654 nonn %O A214654 1,3 %A A214654 _Paul D. Hanna_, Jul 24 2012 %E A214654 Program in Mathematica improved by _Vaclav Kotesovec_, Feb 21 2014