A064166 Composite numbers the sum of the digits in the prime factors of which, with repetition, is prime.

6, 10, 12, 28, 33, 39, 40, 45, 46, 48, 51, 54, 55, 56, 57, 58, 63, 66, 75, 80, 82, 85, 90, 91, 93, 94, 96, 102, 108, 111, 130, 133, 147, 154, 156, 159, 166, 172, 175, 177, 178, 182, 184, 190, 207, 210, 213, 217, 219, 220, 224, 226, 228, 232, 237, 238, 244, 245

Offset

0,1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Example

220 is included because 220 = 2*2*5*11 and 2+2+5+1+1 = 11, which is prime.

Mathematica

cnpQ[n_]:=CompositeQ[n]&&PrimeQ[Total[Flatten[IntegerDigits/@(Table[ #[[1]], #[[2]]]&/@FactorInteger[n])]]]; Select[Range[250], cnpQ] (* Harvey P. Dale, Sep 15 2016 *)

Crossrefs

Sequence in context: A342648 A297620 A074924 * A373678 A107371 A340874

Adjacent sequences: A064163 A064164 A064165 * A064167 A064168 A064169

Keyword

nonn,base

Author

Harvey P. Dale, Sep 19 2001

Status

approved