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A165502
Primes p where the digital sum of p^2 is equal to 31.
6
83, 137, 173, 223, 263, 277, 281, 367, 443, 457, 547, 587, 673, 677, 691, 727, 853, 857, 907, 911, 997, 1033, 1087, 1109, 1163, 1181, 1213, 1217, 1307, 1433, 1447, 1523, 1613, 1627, 1699, 1721, 1811, 2027, 2153, 2203, 2221, 2297, 2347, 2459, 2473, 2477, 2531, 2549
OFFSET
1,1
LINKS
FORMULA
{A000040(i) : A123157(i) = 31} [R. J. Mathar, Sep 29 2009]
EXAMPLE
83 is in the sequence because 83^2=6889 and 6+8+8+9=31.
1721 is in the sequence because 1721^2=2961841 and 2+9+6+1+8+4+1=31.
MAPLE
A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end:
A123157 := proc(n) A007953((ithprime(n))^2) ; end:
for n from 1 to 10000 do if A123157(n) = 31 then printf("%d, ", ithprime(n)) ; fi; od: # R. J. Mathar, Sep 29 2009
MATHEMATICA
Select[Prime[Range[500]], Total[IntegerDigits[#^2]]== 31 &] (* Harvey P. Dale, Apr 13 2011 *)
PROG
(Magma) [p: p in PrimesUpTo(2600) | &+Intseq(p^2) eq 31]; // Vincenzo Librandi, Sep 12 2013
CROSSREFS
Sequence in context: A210527 A140038 A260495 * A126711 A039548 A141976
KEYWORD
nonn,base
AUTHOR
Vincenzo Librandi, Sep 21 2009
EXTENSIONS
Edited by R. J. Mathar, Sep 29 2009
STATUS
approved