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Search: id:A121642
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| A121642 |
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Numbers with composite sum of digits and prime sum of cubes of digits. |
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+0
1
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| 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; listen)
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OFFSET
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1,1
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EXAMPLE
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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.
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MATHEMATICA
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sod[k_, m_] := Plus @@ (IntegerDigits[k]^m); Select[ Table[n, {n, 10000}], (! PrimeQ[sod[ #, 1]] && PrimeQ[sod[ #, 3]]) &]
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CROSSREFS
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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: A108252 A045261 A101039 this_sequence A035886 A043404 A015065
Adjacent sequences: A121639 A121640 A121641 this_sequence A121643 A121644 A121645
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KEYWORD
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base,nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), Sep 08 2006
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