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 A144681 #11 Oct 02 2024 07:54:20 %S A144681 1,1,3,22,305,6656,204337,8226436,414585425,25315924960,1828704716801, %T A144681 153433983789164,14739472821255481,1602471473448455104, %U A144681 195300935112810494801,26470100501608768436716 %N A144681 E.g.f. satisfies: A(x/A(x)) = exp(x). %H A144681 Vaclav Kotesovec, <a href="/A144681/b144681.txt">Table of n, a(n) for n = 0..136</a> %F A144681 E.g.f. satisfies: A(x) = exp( x*A(log A(x)) ). %F A144681 E.g.f. satisfies: a(n+1) = [x^n/n!] exp(x)*A(x)^(n+1). %F A144681 E.g.f: A(x) = G(2x)^(1/2) where G(x/G(x)^2) = exp(x) and G(x) is the e.g.f. of A144682. %F A144681 E.g.f: A(x) = G(3x)^(1/3) where G(x/G(x)^3) = exp(x) and G(x) is the e.g.f. of A144683. %F A144681 E.g.f: A(x) = G(4x)^(1/4) where G(x/G(x)^4) = exp(x) and G(x) is the e.g.f. of A144684. %F A144681 E.g.f: A(x) = 1/G(-x) where G(x*G(x)) = exp(x) and G(x) is the e.g.f. of A087961. %F A144681 E.g.f. A(log(A(x))) = log(A(x))/x = G(x) is the e.g.f of A140049 where G(x) satisfies G(x*exp(-x*G(x))) = exp(x*G(x)). %e A144681 E.g.f. A(x) = 1 + x + 3*x^2/2! + 22*x^3/3! + 305*x^4/4! +... %e A144681 A(x/A(x)) = 1 + x + x^2/2! + x^3/3! + x^4/4! + x^5/5! +... %e A144681 1/A(x) = 1 + x - x^2/2! + 10*x^3/3! - 159*x^4/4! + 3816*x^5/5! -+... %e A144681 A(log(A(x))) = 1 + x + 5*x^2/2! + 55*x^3/3! + 1005*x^4/4! + 26601*x^5/5! +... %e A144681 ILLUSTRATE FORMULA a(n+1) = [x^n/n!] exp(x)*A(x)^(n+1) as follows. %e A144681 Form a table of coefficients of x^k/k! in exp(x)*A(x)^n for n>=1, k>=0: %e A144681 exp(x)*A(x)^1: [(1), 2, 6, 35, 416, 8437, 249340, ...]; %e A144681 exp(x)*A(x)^2: [1,(3), 13, 93, 1145, 22593, 645741, ...]; %e A144681 exp(x)*A(x)^3: [1, 4,(22), 181, 2320, 45199, 1257364, ...]; %e A144681 exp(x)*A(x)^4: [1, 5, 33,(305), 4097, 79825, 2177329, ...]; %e A144681 exp(x)*A(x)^5: [1, 6, 46, 471,(6656), 131001, 3529836, ...]; %e A144681 exp(x)*A(x)^6: [1, 7, 61, 685, 10201,(204337), 5477005, ...]; %e A144681 exp(x)*A(x)^7: [1, 8, 78, 953, 14960, 306643,(8226436), ...]; ... %e A144681 then the terms along the main diagonal form this sequence shift left. %o A144681 (PARI) {a(n)=local(A=1+x+x*O(x^n));for(n=0,n,A=exp(serreverse(x/A)));n!*polcoeff(A,n)} %o A144681 (PARI) {a(n)=local(A=1+x+sum(k=2,n-1,a(k)*x^k/k!)+x*O(x^n));if(n==0,1,(n-1)!*polcoeff(exp(x+x*O(x^n))*A^n,n-1))} %Y A144681 Cf. A144682, A144683, A144684, A087961, A140049. %K A144681 nonn %O A144681 0,3 %A A144681 _Paul D. Hanna_, Sep 19 2008