OFFSET
1,1
COMMENTS
For a subset of these, namely p=179, 239, 359, 419, etc, sigma(p+1) is even larger than 3*p.
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..5000
EXAMPLE
For p=3, the sum of divisors of p+1 is A000203(4)=7 > 2*3, so p=3 is in the sequence.
MATHEMATICA
f[n_]:=Plus@@Divisors[n]; lst={}; Do[p=Prime[n]; If[f[p+1]>2*p, AppendTo[lst, p]], {n, 6!}]; lst
Select[Prime[Range[100]], DivisorSigma[1, # + 1] > 2 # &] (* G. C. Greubel, Sep 13 2017 *)
PROG
(PARI) lista(nn) = forprime(p=2, nn, if (sigma(p+1) > 2*p, print1(p, ", "))); \\ Michel Marcus, Sep 13 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Aug 12 2009
EXTENSIONS
Edited by R. J. Mathar, Aug 21 2009
STATUS
approved