A121642 Numbers with composite sum of digits and prime sum of cubes of digits.

799, 889, 898, 979, 988, 997, 2779, 2797, 2977, 3499, 3949, 3994, 4399, 4588, 4777, 4858, 4885, 4939, 4993, 5488, 5668, 5686, 5848, 5866, 5884, 6568, 6586, 6658, 6667, 6676, 6685, 6766, 6856, 6865, 7099, 7279, 7297, 7477, 7666, 7729, 7747, 7774, 7792

Offset

1,1

Links

Table of n, a(n) for n=1..43.

Example

For example the sum of digits of 799 is 25 which is composite; the sum of the cubes of its digits is 343 + 729 + 729 = 1801, which is prime.

Mathematica

sod[k_, m_] := Plus @@ (IntegerDigits[k]^m); Select[ Table[n, {n, 10000}], (! PrimeQ[sod[ #, 1]] && PrimeQ[sod[ #, 3]]) &]

Crossrefs

Cf. A091365 (Primes p such that the sum of the digits of p is not prime, but the sum of the cubes of the digits of p is prime.) is a subsequence of this sequence.

Sequence in context: A200201 A045261 A101039 * A364087 A035886 A283899

Adjacent sequences: A121639 A121640 A121641 * A121643 A121644 A121645

Keyword

base,nonn

Author

Tanya Khovanova, Sep 08 2006

Status

approved