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A176543
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Numbers n such that semiprime(n)/sum of digits of semiprime(n) is prime.
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1
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7, 36, 44, 63, 68, 79, 128, 148, 157, 192, 244, 303, 323, 335, 410, 421, 475, 483, 535, 606, 616, 669, 776, 849, 862, 868, 947, 964, 986, 1039, 1046, 1256, 1264, 1403, 1406, 1422, 1579, 1700, 1733, 1874, 1971
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..41.
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FORMULA
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A001358(a(n))/A175013(a(n))=prime.
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EXAMPLE
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a(1)=7 because prime=7=21/3=semiprime(7)/sum of digits of semiprime(7); a(2)=36 because prime=37=111/3=semiprime(36)/sum of digits of semiprime(36).
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MAPLE
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A175013 := proc(n) A007953(A001358(n)) ; end proc: A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc: for n from 1 to 2000 do r := A001358(n)/A175013(n) ; if type(r, 'integer') then if isprime(r) then printf("%d, ", n) ; end if; end if; end do: [From R. J. Mathar, Apr 26 2010]
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CROSSREFS
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Sequence in context: A197555 A028389 A041603 * A018199 A063168 A163683
Adjacent sequences: A176540 A176541 A176542 * A176544 A176545 A176546
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KEYWORD
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nonn,base,less
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AUTHOR
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Juri-Stepan Gerasimov, Apr 20 2010
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EXTENSIONS
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More terms from R. J. Mathar, Apr 26 2010
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STATUS
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approved
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