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A107289 Numbers k such that the sum of digits of k^2 is a prime. 1
4, 5, 7, 16, 17, 25, 26, 28, 29, 32, 34, 37, 38, 40, 44, 47, 49, 50, 52, 53, 56, 61, 62, 64, 65, 70, 73, 79, 82, 83, 89, 91, 98, 106, 107, 109, 115, 116, 118, 119, 125, 127, 133, 137, 142, 143, 146, 149, 151, 154, 155, 160, 161, 164, 170, 173, 181, 182, 187, 188, 199 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..61.

FORMULA

a(n) = sqrt(A065408(n)).

MATHEMATICA

bb={}; Do[If[PrimeQ[Apply[Plus, IntegerDigits[n^2]]], bb=Append[bb, n]], {n, 500}]; bb

PROG

(PARI) isok(n) = isprime(sumdigits(n^2)); \\ Michel Marcus, Jan 09 2019

CROSSREFS

Cf. A065408.

Sequence in context: A281991 A216537 A085195 * A056659 A292321 A049896

Adjacent sequences:  A107286 A107287 A107288 * A107290 A107291 A107292

KEYWORD

nonn,base

AUTHOR

Zak Seidov, May 20 2005

STATUS

approved

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Last modified November 17 06:06 EST 2019. Contains 329217 sequences. (Running on oeis4.)