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 A121614 Numbers n that have composite sum of digits and prime sum of squares of digits. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE 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. MATHEMATICA sod[k_, m_] := Plus @@ (IntegerDigits[k]^m); Select[ Table[n, {n, 1000}], (! PrimeQ[sod[ #, 1]] && PrimeQ[sod[ #, 2]]) &] 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. Sequence in context: A253919 A259504 A307373 * A046340 A046316 A046373 Adjacent sequences:  A121611 A121612 A121613 * A121615 A121616 A121617 KEYWORD base,nonn AUTHOR Tanya Khovanova, Sep 08 2006 STATUS approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)