A074054 Numbers n such that sum of composites from smallest prime factor of n to largest prime factor of n is prime.

22, 33, 44, 66, 88, 99, 106, 110, 132, 134, 154, 155, 159, 165, 176, 178, 198, 201, 202, 206, 212, 220, 231, 242, 264, 267, 268, 297, 303, 308, 309, 318, 330, 334, 352, 356, 363, 371, 396, 402, 404, 412, 413, 424, 440, 445, 462, 469, 477, 484, 493, 495, 501

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

22=2*11 and sum of composites between 2 and 11 is: 4+6+8+9+10 = 37, prime.

Mathematica

scpQ[n_]:=Module[{f=Transpose[FactorInteger[n]][[1]], a, b}, a = First[f]+ 1; b=Last[f]-1; PrimeQ[Total[Select[Range[a, b], !PrimeQ[#]&]]]]; Select[ Range[ 510], scpQ] (* Harvey P. Dale, May 07 2013 *)

Crossrefs

Sequence in context: A190588 A072041 A067035 * A067287 A026044 A120146

Adjacent sequences: A074051 A074052 A074053 * A074055 A074056 A074057

Keyword

nonn

Author

Jason Earls, Sep 15 2002

Status

approved