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A329179 Numbers k such that A258881(k) is a square. 4
0, 23, 36, 52, 71, 80, 104, 137, 143, 154, 377, 443, 479, 533, 823, 963, 977, 1013, 1125, 1204, 1284, 1334, 1493, 1624, 1769, 1786, 1997, 2047, 2110, 2228, 2260, 2427, 2508, 2577, 2707, 2740, 3121, 3174, 3223, 3407, 3440, 3477, 3526, 3644, 3745, 3828, 3860, 4027, 4079, 4163, 4314, 4384, 4518 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

EXAMPLE

a(3) = 36 is a member of the sequence because 36 + 3^2 + 6^2 = 81 = 9^2.

MAPLE

filter:= n -> issqr(n + convert(map(`^`, convert(n, base, 10), 2), `+`)):

select(filter, [$0..10^4]);

PROG

(Python)

from sympy.ntheory.primetest import is_square

def ssd(n): return sum(int(d)**2 for d in str(n))

def ok(n): return is_square(n + ssd(n))

def aupto(limit): return [m for m in range(limit+1) if ok(m)]

print(aupto(4000)) # Michael S. Branicky, Jan 30 2021

(PARI) isok(k) = issquare(k+norml2(digits(k))); \\ Michel Marcus, Jan 31 2021

CROSSREFS

Cf. A010052, A258881, A329386.

Sequence in context: A120147 A166499 A045533 * A154114 A163384 A291689

Adjacent sequences:  A329176 A329177 A329178 * A329180 A329181 A329182

KEYWORD

base,nonn

AUTHOR

Will Gosnell and Robert Israel, Nov 07 2019

STATUS

approved

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Last modified March 9 03:31 EST 2021. Contains 341961 sequences. (Running on oeis4.)