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A333475 Numbers k such that S(2^k) is a perfect square, where S(t) is the sum of decimal digits of t. 1
0, 2, 16, 22, 36, 78, 104, 110, 118, 130, 176, 186, 194, 200, 216, 240, 270, 276, 320, 358, 364, 376, 440, 558, 576, 602, 608, 612, 614, 620, 630, 700, 872, 884, 894, 918, 972, 1144, 1174, 1192, 1216, 1536, 1566, 1610, 1658, 1798, 1882, 2000, 2312, 2630, 2928, 3042, 3540, 3648, 3744, 3750, 3774 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers k such that A000079(k) is in A028839.

All terms are even. - Robert Israel, Mar 24 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..209

EXAMPLE

16 is in the sequence, because S(2^16) = S(65536) = 25 is a perfect square.

MAPLE

sd:= n -> convert(convert(n, base, 10), `+`):

select(t -> issqr(sd(2^t)), [$0..10000]); # Robert Israel, Mar 24 2020

PROG

(PARI) isok(k) = issquare(sumdigits(2^k)); \\ Michel Marcus, Mar 23 2020

CROSSREFS

Cf. A000079, A007953, A028839.

Sequence in context: A271627 A118954 A119599 * A330611 A228158 A330662

Adjacent sequences:  A333472 A333473 A333474 * A333476 A333477 A333478

KEYWORD

nonn,base

AUTHOR

Daniel Starodubtsev, Mar 23 2020

STATUS

approved

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Last modified May 25 10:05 EDT 2022. Contains 354066 sequences. (Running on oeis4.)