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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 12 07:28 EDT 2021. Contains 343821 sequences. (Running on oeis4.)