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A121642 Numbers with composite sum of digits and prime sum of cubes of digits. 0
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 (list; graph; refs; listen; history; text; internal format)
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 * A035886 A043404 A015065

Adjacent sequences:  A121639 A121640 A121641 * A121643 A121644 A121645

KEYWORD

base,nonn

AUTHOR

Tanya Khovanova, Sep 08 2006

STATUS

approved

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Last modified January 24 12:17 EST 2017. Contains 281237 sequences.