A261726 - OEIS

%I #21 Apr 01 2021 15:27:58

%S 2,6,15,210,66,1820,153,7315,376740,435,1947792,91390,861,163185,

%T 20358520,40475358,1770,90858768,916895,2556,256851595,1749060,

%U 541931236,132601016340,3921225,5151,4967690,5778,6210820,1378095785451705375,11358880,7858539612

%N a(n) = binomial(prime(n+1)-1, prime(n)-1).

%H Harvey P. Dale, <a href="/A261726/b261726.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = binomial(prime(n+1)-1, prime(n)-1).

%e For n = 2, a(n) = binomial(prime(n+1)-1, prime(n)-1) = binomial(4,2) = 6.

%t Binomial[#[[2]]-1,#[[1]]-1]&/@Partition[Prime[Range[40]],2,1] (* _Harvey P. Dale_, Apr 01 2021 *)

%o (PARI) a(n) = binomial(prime(n+1)-1, prime(n)-1);

%o vector(35, n, a(n))

%Y Cf. A000040, A001700, A104861.

%K nonn,easy

%O 1,1

%A _Altug Alkan_, Sep 14 2015