OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

EXAMPLE

For example: the sum of digits of 27 is 9 which is composite; the sum of squares of digits of 27 is 53 which is prime.

MATHEMATICA

sod[k_, m_] := Plus @@ (IntegerDigits[k]^m); Select[ Table[n, {n, 1000}], (! PrimeQ[sod[ #, 1]] && PrimeQ[sod[ #, 2]]) &]

CROSSREFS

Cf. A091362 (Primes p such that the sum of the digits of p is not prime, but the sum of the squares of the digits of p is prime) is a prime subsequence of this sequence.

KEYWORD

base,nonn

AUTHOR

Tanya Khovanova, Sep 08 2006

STATUS

approved