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Sum of divisors of p+1, p prime.
14

%I #28 Apr 19 2020 07:52:35

%S 4,7,12,15,28,24,39,42,60,72,63,60,96,84,124,120,168,96,126,195,114,

%T 186,224,234,171,216,210,280,216,240,255,336,288,336,372,300,240,294,

%U 480,360,546,336,508,294,468,465,378,504,560,432,546,744,399,728,528,720,720,558

%N Sum of divisors of p+1, p prime.

%H Vincenzo Librandi, <a href="/A008333/b008333.txt">Table of n, a(n) for n = 1..999</a> (offset adapted by Michel Marcus)

%F a(n) = A000203(A008864(n)). - _Michel Marcus_, May 11 2016

%F a(n) = A000203(A000203(prime(n))) = A051027(prime(n)). - _Michel Marcus_, May 11 2016

%p for i from 1 to 500 do if isprime(i) then print(sigma(i+1)); fi; od;

%t lst={};Do[AppendTo[lst, DivisorSigma[1, Prime[n]+1]], {n, 6!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Sep 20 2008 *)

%o (PARI) a(n) = sigma(prime(n)+1); \\ _Michel Marcus_, May 11 2016

%Y Cf. A000203, A008864, A051027.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_

%E Offset 1 from _Michel Marcus_, Apr 19 2020