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A036917 a(n) = (16*(n-1/2)*(2*n^2-2*n+1)*a(n-1)-256*(n-1)^3*a(n-2))/n^3. 40
1, 8, 88, 1088, 14296, 195008, 2728384, 38879744, 561787864, 8206324928, 120929313088, 1794924383744, 26802975999424, 402298219288064, 6064992788397568, 91786654611673088, 1393772628452578264, 21227503080738294464, 324160111169327247424 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

REFERENCES

M. Petkovsek et al., "A=B", Peters, p. ix of second printing.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 0..500

B. Adamczewski, J. P. Bell, E. Delaygue, Algebraic independence of G-functions and congruences "a la Lucas", arXiv preprint arXiv:1603.04187 [math.NT], 2016.

E. Delaygue, Arithmetic properties of Apery-like numbers, arXiv preprint arXiv:1310.4131 [math.NT], 2013.

N. J. A. Sloane, My favorite integer sequences, in Sequences and their Applications (Proceedings of SETA '98).

FORMULA

a(n) = Sum_{k=0..n} (C(2 * (n-k), n-k) * C(2 * k, k))^2.

G.f.: (4/Pi^2)*EllipticK(4*x^(1/2))^2. - Vladeta Jovovic, Dec 01 2003

a(n) = hypergeom([1/2, 1/2, -n, -n], [1, 1/2-n, 1/2-n], 1) * 4^n * (2n-1)!!^2 / n!^2. - Vladimir Reshetnikov, Mar 08 2014

a(n) ~ 2^(4*n+1) * log(n) / (n*Pi^2) * (1 + (4*log(2) + gamma)/log(n)), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Nov 28 2015

MATHEMATICA

a[n_] := (16 (n - 1/2)(2*n^2 - 2*n + 1)a[n - 1] - 256(n - 1)^3 a[n - 2])/n^3; a[0] = 1; a[1] = 8; Array[a, 19, 0] (* Or *)

f[n_] := Sum[(Binomial[2 (n - k), n - k] Binomial[2 k, k])^2, {k, 0, n}]; Array[f, 19, 0] (* Or *)

lmt = 20; Take[ 4^Range[0, 2 lmt]*CoefficientList[ Series[(4/Pi^2) EllipticK[4 x^(1/2)]^2, {x, 0, lmt}], x^(1/2)], lmt] (* Robert G. Wilson v *)

a[n_] := HypergeometricPFQ[{1/2, 1/2, -n, -n}, {1, 1/2-n, 1/2-n}, 1] * 4^n * (2n-1)!!^2 / n!^2 (* Vladimir Reshetnikov, Mar 08 2014 *)

PROG

(Haskell)

a036917 n = sum $ map

   (\k -> (a007318 (2*n-2*k) (n-k))^2 * (a007318 (2*k) k)^2) [0..n]

-- Reinhard Zumkeller, May 24 2012

(PARI) for(n=0, 25, print1(sum(k=0, n, (binomial(2*n-2*k, n-k) *binomial(2*k, k))^2), ", ")) \\ G. C. Greubel, Oct 24 2017

CROSSREFS

Cf. A036915, A057703.

Cf. A007318, A036916, A036829.

The Apéry-like numbers [or Apéry-like sequences, Apery-like numbers, Apery-like sequences] include A000172, A000984, A002893, A002895, A005258, A005259, A005260, A006077, A036917, A063007, A081085, A093388, A125143 (apart from signs), A143003, A143007, A143413, A143414, A143415, A143583, A183204, A214262, A219692,A226535, A227216, A227454, A229111 (apart from signs), A260667, A260832, A262177, A264541, A264542, A279619, A290575, A290576. (The term "Apery-like" is not well-defined.)

Sequence in context: A250166 A247738 A115864 * A003497 A051605 A271268

Adjacent sequences:  A036914 A036915 A036916 * A036918 A036919 A036920

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

First formula corrected by Tito Piezas III, Oct 19 2010

STATUS

approved

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Last modified February 23 07:47 EST 2018. Contains 299473 sequences. (Running on oeis4.)