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A121642 Numbers with composite sum of digits and prime sum of cubes of digits. 0

%I #2 Mar 30 2012 18:49:08

%S 799,889,898,979,988,997,2779,2797,2977,3499,3949,3994,4399,4588,4777,

%T 4858,4885,4939,4993,5488,5668,5686,5848,5866,5884,6568,6586,6658,

%U 6667,6676,6685,6766,6856,6865,7099,7279,7297,7477,7666,7729,7747,7774,7792

%N Numbers with composite sum of digits and prime sum of cubes of digits.

%e 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.

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

%Y 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.

%K base,nonn

%O 1,1

%A _Tanya Khovanova_, Sep 08 2006

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Last modified July 2 23:09 EDT 2024. Contains 373960 sequences. (Running on oeis4.)