A257284 Numbers n not divisible by 2 such that n^2 written in base 4 has no digit > 1.

1, 9, 33, 129, 513, 1175, 2049, 4617, 8193, 18441, 18807, 32769, 73737, 131073, 264321, 270369, 294921, 524289, 545431, 1081377, 1179657, 2097153, 4203009, 4325409, 4718601, 8388609, 16810497, 16908417, 17301537, 18874377, 33554433, 38729961, 67143681, 67633281, 69206049

Offset

1,2

Comments

The first condition is added to exclude terms of the form a(k)*2^m (m>0), whose square would just have 0's appended w.r.t. a(k)^2 when written in base 4, and therefore trivially have no digit > 1 in base 4.

See A230030 for the base 5 analog, which is much more challenging.

Links

Table of n, a(n) for n=1..35.

Prog

(PARI) b=4; forstep(n=1, 10^8, 2, vecmax(digits(n^2, b))>1||print1(n", "))

Crossrefs

Cf. A257283 (base 3 analog), A230030 (base 5 analog).

Sequence in context: A221447 A147147 A147154 * A257744 A147275 A140413

Adjacent sequences: A257281 A257282 A257283 * A257285 A257286 A257287

Keyword

nonn,base

Author

M. F. Hasler, May 02 2015

Status

approved