A396929 - OEIS

%I #15 Jun 16 2026 18:30:06

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

%T 9,7,7,7,6,5,9,7,2,0,0,5,8,5,3,6,3,6,3,7,1,1,3,1,2,6,0,5,6,9,1,2,9,3,

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

%N Decimal expansion of the sum of the reciprocals of square pyramidal factorials A135438.

%H Kelvin Voskuijl, <a href="/A396929/b396929.txt">Table of n, a(n) for n = 1..10000</a>

%F Equals hypergeom([], [3/2, 2], 3).

%e 2.21477065859645...

%t RealDigits[HypergeometricPFQ[{}, {3/2, 2}, 3], 10, 120][[1]]

%o (PARI) suminf(n=0, 1/((n+1)!*(2*n+1)!/12^n))

%Y Cf. A135438.

%Y Cf. A001113, A070910, A271574, A396449, A396450, A396451, A396929, A396930, A396931, A396932, A396933.

%K nonn,cons

%O 1,1

%A _Kelvin Voskuijl_, Jun 11 2026