This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A023840 #10 Jun 14 2025 04:18:26
%S A023840 0,3,5,5,7,8,8,11,11,10,12,14,13,14,16,16,14,18,17,17,18,18,19,25,23,
%T A023840 23,25,24,23,24,23,26,24,24,25,26,27,27,28,29,25,30,32,31,31,30,33,36,
%U A023840 33,37,38,38,39,40,36,40,39,39,39,41,38,39,43,42,37,38,41,42,44,43,43,45,43,46,50,48,49
%N A023840 Sum of exponents in prime-power factorization of C(5n,n-3).
%H A023840 Ivan Neretin, <a href="/A023840/b023840.txt">Table of n, a(n) for n = 3..10000</a>
%F A023840 From _Amiram Eldar_, Jun 14 2025: (Start)
%F A023840 a(n) = A001222(A004345(n)).
%F A023840 a(n) = A023838(n) - A001222(4*n+3) + A001222(n-2). (End)
%t A023840 Table[PrimeOmega[Binomial[5 n, n - 3]], {n, 3, 79}] (* _Ivan Neretin_, Nov 08 2017 *)
%o A023840 (PARI) a(n) = bigomega(binomial(5*n,n-3)); \\ _Amiram Eldar_, Jun 14 2025
%Y A023840 Cf. A001222, A004345, A023837, A023838, A023839, A023841, A023842, A023843, A023844, A023845, A023846, A023847, A023848, A023849, A023850, A023851.
%K A023840 nonn
%O A023840 3,2
%A A023840 _Clark Kimberling_
%E A023840 Offset corrected to 3 by _Ivan Neretin_, Nov 08 2017