The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A352011 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} (-4)^k * a(k) * a(n-2*k-1). 2
 1, 1, 1, -3, -7, 5, 33, 269, 393, -1451, -4815, -14115, -2791, 171685, 398145, -3887699, -10399319, 6567925, 63031889, 558518141, 853157689, -4400392635, -14954126751, 29904043597, 151457170889, 344861133205, 170895616881, -12627954103779, -30049168949927 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Table of n, a(n) for n=0..28. FORMULA G.f. A(x) satisfies: A(x) = 1 / (1 - x * A(-4*x^2)). MATHEMATICA a[0] = 1; a[n_] := a[n] = Sum[(-4)^k a[k] a[n - 2 k - 1], {k, 0, Floor[(n - 1)/2]}]; Table[a[n], {n, 0, 28}] nmax = 28; A[_] = 0; Do[A[x_] = 1/(1 - x A[-4 x^2]) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x] CROSSREFS Cf. A015099, A101912, A352009, A352010. Sequence in context: A161509 A108974 A106853 * A083778 A107785 A277207 Adjacent sequences: A352008 A352009 A352010 * A352012 A352013 A352014 KEYWORD sign AUTHOR Ilya Gutkovskiy, Feb 28 2022 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 February 28 08:11 EST 2024. Contains 370393 sequences. (Running on oeis4.)