A130075 - OEIS

%I #12 Jun 08 2021 07:57:57

%S 6,30,570,10830,4422630,93776970,44871187170,1003806502230,

%T 518297165370030,6422911941109705770,150213298561349961630,

%U 1966475018690546370358170,1109139879321302763891656370

%N a(n) = (5^p - 3^p - 2^p)/p, where p = prime(n).

%C p divides 5^p - 3^p - 2^p = A130072(p) for prime p.

%C p^(k+1) divides A130072(p^k) for prime p = {2,3,5,19} = A130076(n) and all k>0.

%C 2 divides a(n). 3 divides a(n). 5 divides a(n) for n>1. 19 divides a(n) for n>2. 19^2 divides a(n) for n in A091178(n) or prime(n) in A002476.

%F a(n) = (5^prime(n) - 3^prime(n) - 2^prime(n))/prime(n).

%F a(n) = A130072(prime(n))/prime(n).

%t Table[(5^Prime[n]-3^Prime[n]-2^Prime[n])/Prime[n],{n,1,20}]

%t (5^#-3^#-2^#)/#&/@Prime[Range[20]] (* _Harvey P. Dale_, May 02 2012 *)

%Y Cf. A130072, A130073, A130074, A130076, A091178, A002476.

%K nonn

%O 1,1

%A _Alexander Adamchuk_, May 06 2007