A023841 Sum of exponents in prime-power factorization of C(5n,n-4).

0, 2, 3, 4, 5, 6, 9, 9, 9, 10, 11, 10, 12, 13, 15, 13, 15, 16, 15, 15, 16, 17, 21, 22, 22, 22, 24, 19, 21, 22, 23, 23, 23, 23, 24, 25, 25, 25, 28, 24, 26, 31, 29, 27, 29, 30, 33, 33, 36, 35, 36, 36, 37, 36, 39, 37, 38, 37, 37, 34, 36, 40, 42, 38, 36, 39, 40, 40, 42, 42, 41, 43, 43, 47, 48, 45, 46, 47

Offset

4,2

Links

Ivan Neretin, Table of n, a(n) for n = 4..10000

Formula

From Amiram Eldar, Jun 14 2025: (Start)

a(n) = A001222(A004346(n)).

a(n) = A023840(n) - A001222(4*n+4) + A001222(n-3). (End)

Mathematica

Table[PrimeOmega[Binomial[5 n, n - 4]], {n, 4, 81}] (* Ivan Neretin, Nov 08 2017 *)

Prog

(PARI) a(n) = bigomega(binomial(5*n, n-4)); \\ Amiram Eldar, Jun 14 2025

Crossrefs

Cf. A001222, A004346, A023837, A023838, A023839, A023840, A023842, A023843, A023844, A023845, A023846, A023847, A023848, A023849, A023850, A023851.

Sequence in context: A245705 A075164 A240827 * A340553 A380817 A245605

Adjacent sequences: A023838 A023839 A023840 * A023842 A023843 A023844

Keyword

nonn

Author

Clark Kimberling

Extensions

Offset corrected to 4 by Ivan Neretin, Nov 08 2017

Status

approved