OFFSET
1,3
COMMENTS
Trivially includes powers of 16, since 16^k = 100..00_4 = 10^(2k) when read as a base-10 number. Moreover, for any a(n) in the sequence, 16*a(n) is also in the sequence. One could call "primitive" the terms not of this form, these would be 1, 25 = 121_4, 289 = 10201_4, 441 = 12321_4, 673 = 22201_4, 1761 = 123201_4, ... These primitive terms include the subsequence 16^k + 2*4^k + 1 = (4^k+1)^2, k > 0, which yields A033934 when written in base 4.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[1000], IntegerQ[Sqrt[FromDigits[IntegerDigits[#, 4]]]] &] (* Alonso del Arte, Jan 23 2016 *)
PROG
(PARI) is(n, b=4, c=10)=issquare(subst(Pol(digits(n, b)), x, c))
(Python)
A267764_list = [int(d, 4) for d in (str(i**2) for i in range(10**6)) if max(d) < '4'] # Chai Wah Wu, Feb 23 2016
CROSSREFS
KEYWORD
nonn,base
AUTHOR
M. F. Hasler, Jan 20 2016
STATUS
approved