The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A135867 G.f. satisfies A(x) = 1 + x*A(2*x)^2. 11
 1, 1, 4, 36, 640, 21888, 1451008, 188941312, 48768745472, 25069815595008, 25722272102744064, 52730972085034156032, 216091838647321476726784, 1770657164881170759078117376, 29013990909330956353981535748096 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Self-convolution equals A135868 such that 2^n*A135868(n) = a(n+1) for n >= 0. LINKS Seiichi Manyama, Table of n, a(n) for n = 0..81 FORMULA a(n) = 2^(n-1)*Sum_{k=0..n-1} a(k)*a(n-k-1) for n>0 with a(0)=1. - Paul D. Hanna, Feb 09 2010 a(n) ~ c * 2^(n*(n+1)/2), where c = 0.715337433614869740944075474484711589980951273610257702786245519231799678... - Vaclav Kotesovec, Nov 04 2021 MATHEMATICA nmax = 15; A[_] = 0; Do[A[x_] = 1 + x*A[2*x]^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] (* Vaclav Kotesovec, Nov 04 2021 *) PROG (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A, x, 2*x)^2); polcoeff(A, n)} (PARI) a(n)=if(n==0, 1, 2^(n-1)*sum(k=0, n-1, a(k)*a(n-k-1))) \\ Paul D. Hanna, Feb 09 2010 CROSSREFS Cf. A015083, A135868, A171192. Cf. A171200, A171202, A171204, A171206, A171208, A171210, A343439. Sequence in context: A241029 A002761 A002084 * A268470 A365650 A214347 Adjacent sequences: A135864 A135865 A135866 * A135868 A135869 A135870 KEYWORD nonn AUTHOR Paul D. Hanna, Dec 02 2007 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 24 04:41 EDT 2024. Contains 372772 sequences. (Running on oeis4.)