A121614 Numbers that have composite sum of digits and prime sum of squares of digits.

27, 45, 54, 72, 78, 87, 126, 159, 162, 168, 186, 195, 207, 216, 234, 243, 249, 261, 267, 270, 276, 294, 324, 342, 348, 357, 375, 384, 405, 423, 429, 432, 438, 450, 483, 492, 504, 519, 537, 540, 573, 591, 612, 618, 621, 627, 672, 678, 681, 687, 702, 708, 720

Offset: 1

Author

Tanya Khovanova, Sep 08 2006

Keywords

• base
• nonn

Examples

			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.
		

Links

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

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.

Programs

Mathematica

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