

A175396


Numbers n such that the sum of the squares of its digits is a perfect square.


7



0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 34, 40, 43, 50, 60, 68, 70, 80, 86, 90, 100, 122, 148, 184, 200, 212, 221, 236, 244, 263, 269, 296, 300, 304, 326, 340, 362, 366, 400, 403, 418, 424, 430, 442, 447, 474, 481, 488, 500, 600, 608, 623, 629, 632, 636, 663
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OFFSET

1,3


COMMENTS

Previous name was: Numbers n such that Sum_{i=1..r, x(i)^2} is a perfect square, where x(i) = digits of n. r=1+floor(log_10 n).


LINKS

Christian N. K. Anderson, Table of n, a(n) for n = 1..10000


EXAMPLE

n=34, 3*3+4*4=25 is a perfect square so n=34 belongs to the sequence. n=122, 1*1+2*2+2*2=9 is a perfect square so n=122 belongs to the sequence.


MATHEMATICA

Select[Range[0, 666], IntegerQ[Sqrt[Plus @@ (IntegerDigits[#]^2)]] &] (* Ivan Neretin, Aug 03 2015 *)


PROG

(PARI) isok(n) = {digs = Vec(Str(n)); issquare(sum(i=1, #digs, eval(digs[i])^2))} \\ Michel Marcus, Jun 02 2013


CROSSREFS

Cf. A084561.
Sequence in context: A108652 A140665 A069024 * A107085 A212499 A244890
Adjacent sequences: A175393 A175394 A175395 * A175397 A175398 A175399


KEYWORD

base,easy,nonn


AUTHOR

Ctibor O. Zizka, Apr 30 2010


EXTENSIONS

Corrected and extended by Neven Juric, Jul 12 2010
Simpler definition by Michel Marcus, Jun 02 2013


STATUS

approved



