A277520 Denominator of 3F2([3*n, -n, n+1],[2*n+1, n+1/2], 1).

1, 3, 25, 147, 1089, 20449, 48841, 312987, 55190041, 14322675, 100100025, 32065374675, 4546130625, 29873533563, 1859904071089, 4089135109921, 9399479144449, 22568149425822049, 1293753708921104809, 2835106739783283, 3289668853728536041

Offset

0,2

Comments

Neil Calkin found the closed forms of 3F2([3*n, -n, n+1],[2*n+1, n+1/2], 1) in 2007.

References

Jonathan Borwein, David Bailey, Mathematics by Experiment, 2nd Edition: Plausible Reasoning in the 21st Century.

Links

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Formula

(s(n) =) 3F2([3*n, -n, n+1],[2*n+1, n+1/2], 1) = A277170(n) / a(n).

s(2k) = (A005810(k) / A066802(k))^2 = (((4k)! * (3k)!) / ((6k)! * k!))^2.

s(2k+1) = -1/3 * (A052203(k) / A187364(k))^2 = -1/3 * (((4k+1)! * (3k)!) / ((6k+1)! * k!))^2.

Mathematica

a[n_] := HypergeometricPFQ[{3n, -n, n+1}, {2n+1, n+1/2}, 1] // Denominator;
Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Oct 22 2016 *)

Crossrefs

Cf. A005810, A052203, A066802, A187364, A277170 (numerators).

Sequence in context: A265874 A144646 A308417 * A367507 A303602 A000544

Adjacent sequences: A277517 A277518 A277519 * A277521 A277522 A277523

Keyword

nonn,frac

Author

Seiichi Manyama, Oct 19 2016

Status

approved