A048977 Primes arising in A048969.

3, 7, 13, 19, 31, 61, 127, 127, 331, 307, 307, 631, 1801, 1723, 3169, 1093, 1723, 3571, 1093, 3221, 5419, 3541, 3541, 8269, 5113, 5113, 13267, 8011, 8011, 16651, 10303, 19441, 10303, 24571, 17293, 17293, 28057, 30103, 55897, 28057, 59221, 30103, 8191, 19531

Offset: 1

Author

G. L. Honaker, Jr.

Keywords

• nonn

Crossrefs

Cf. A048968, A048969.

Programs

Mathematica

p[n_]:=Module[{c=DivisorSigma[1,n]/DivisorSigma[0,n]},If[PrimeQ[c],c,0]]; nn=62000;With[{comps=Complement[Range[nn],Prime[Range[PrimePi[nn]]]]}, Select[ p/@comps,#!=0&]] (* Harvey P. Dale, Feb 19 2012 *)

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jun 17 2001

More terms from Sean A. Irvine, Jul 16 2021