A165502 Primes p where the digital sum of p^2 is equal to 31.

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

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

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

Adjacent sequences: A165499 A165500 A165501 * A165503 A165504 A165505

Keyword

nonn,base

Author

Vincenzo Librandi, Sep 21 2009

Extensions

Edited by R. J. Mathar, Sep 29 2009

Status

approved