

A071179


n  (sum of prime factors of n) is prime.


1



4, 10, 12, 14, 15, 18, 20, 21, 24, 26, 28, 33, 35, 36, 38, 39, 44, 45, 48, 50, 51, 52, 56, 62, 63, 65, 69, 72, 75, 77, 80, 86, 91, 92, 93, 95, 98, 104, 108, 111, 112, 117, 122, 123, 129, 133, 135, 144, 146, 147, 148, 152, 159, 161, 162, 171, 172, 175, 176, 188, 189
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OFFSET

1,1


COMMENTS

Prime factors taken without multiplicity.  Harvey P. Dale, Feb 04 2014


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..2000


EXAMPLE

20 = 2^2.5 and 20(2+5) = 13 is prime hence 20 is in the sequence


MATHEMATICA

Select[Range[200], PrimeQ[#Total[Transpose[FactorInteger[#]][[1]]]]&] (* Harvey P. Dale, Feb 04 2014 *)


PROG

(PARI) for(n=1, 100, if(isprime(nsumdiv(n, d, isprime(d)*d))==1, print1(n, ", ")))


CROSSREFS

Sequence in context: A092428 A170943 A102998 * A155475 A023693 A181053
Adjacent sequences: A071176 A071177 A071178 * A071180 A071181 A071182


KEYWORD

easy,nonn


AUTHOR

Benoit Cloitre, Jun 10 2002


STATUS

approved



