A114080 Numbers k such that sigma(k) times the k-th prime is a brilliant number (A078972).

2, 4, 9, 16, 25, 64, 729, 65536

Offset

1,1

Comments

No additional terms up to 1 million. - Harvey P. Dale, Nov 13 2013

Links

Table of n, a(n) for n=1..8.

Example

sigma(25) * p(25) = 3007 = 31*97.

Mathematica

brilQ[n_]:=Module[{pf=Transpose[FactorInteger[n]][[1]]}, PrimeOmega[n] == 2&&IntegerLength[First[pf]]==IntegerLength[Last[pf]]]; Select[Range[ 100000], brilQ[DivisorSigma[1, #]Prime[#]]&] (* Harvey P. Dale, Nov 13 2013 *)

Crossrefs

Sequence in context: A364131 A077137 A023194 * A090676 A333779 A261240

Adjacent sequences: A114077 A114078 A114079 * A114081 A114082 A114083

Keyword

nonn,base

Author

Giovanni Resta, Feb 13 2006

Status

approved