login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Greatest exponent in prime-power factorization of 2*prime(n)+1.
2

%I #12 Sep 09 2024 02:40:46

%S 1,1,1,1,1,3,1,1,1,1,2,2,1,1,1,1,1,1,3,1,2,1,1,1,1,1,2,1,1,1,1,1,2,2,

%T 1,1,2,1,1,1,1,2,1,2,1,1,2,1,1,3,1,1,1,1,1,1,2,1,1,1,4,1,1,1,1,1,1,3,

%U 1,1,1,1,2,2,1,1,1,1,1,2,1,1,1,2,1,1,1,1,1,2,1,1,2,1,3,1,1,1,1

%N Greatest exponent in prime-power factorization of 2*prime(n)+1.

%F a(n) = A051903(A072055(n)). - _Amiram Eldar_, Sep 09 2024

%p A023591 := proc(n)

%p A051903(2*ithprime(n)+1) ;

%p end proc: # _R. J. Mathar_, Jul 08 2015

%t a[n_] := Max[FactorInteger[2*Prime[n] + 1][[;;, 2]]]; Array[a, 100] (* _Amiram Eldar_, Sep 09 2024 *)

%o (PARI) a(n) = vecmax(factor(2*prime(n)+1)[,2]); \\ _Michel Marcus_, Apr 20 2021

%Y Cf. A051903, A072055.

%K nonn

%O 1,6

%A _Clark Kimberling_