A395756 Decimal expansion of the sum of the reciprocals of the 9-gonal polygorials A084942.

2, 1, 1, 5, 8, 4, 2, 7, 3, 8, 9, 5, 3, 0, 2, 8, 6, 2, 9, 3, 7, 1, 1, 5, 2, 5, 0, 6, 8, 5, 8, 4, 4, 8, 8, 9, 1, 9, 4, 2, 9, 4, 8, 5, 4, 6, 3, 6, 0, 9, 0, 8, 4, 9, 4, 2, 1, 6, 3, 8, 0, 4, 2, 3, 8, 4, 2, 5, 8, 7, 1, 4, 2, 3, 9, 1, 0, 8, 6, 6, 5, 0, 0, 0, 9, 3, 2, 0, 9, 3, 3, 8, 2, 8, 9, 9, 3, 2, 9, 5, 3, 9, 2, 5, 3, 0, 9, 1, 7, 9, 0

Offset

1,1

Links

Kelvin Voskuijl, Table of n, a(n) for n = 1..10000

Formula

Equals (2/7)^(5/14) * BesselI(-5/7, 2*sqrt(2/7)) * Gamma(2/7).

Example

2.115842738953028629371...

Mathematica

RealDigits[(2/7)^(5/14) BesselI[-5/7, 2 Sqrt[2/7]] Gamma[2/7], 10, 120][[1]]

Prog

(PARI) (2/7)^(5/14) * besseli(-5/7, 2*sqrt(2/7)) * gamma(2/7)

Crossrefs

Cf. A001113 (of factorials), A070910 (of factorials squared).

Cf. A395536-A395537, A395755-A395759 (pentagonal to 12-gonal).

Cf. A084942.

Sequence in context: A049252 A098315 A006704 * A324960 A174986 A375321

Adjacent sequences: A395753 A395754 A395755 * A395757 A395758 A395759

Keyword

nonn,cons

Author

Kelvin Voskuijl, May 05 2026

Status

approved