A305719 Numbers whose squares have the same first and last digits.

1, 2, 3, 11, 22, 26, 39, 41, 68, 75, 97, 101, 109, 111, 119, 121, 129, 131, 139, 141, 202, 208, 212, 218, 222, 225, 235, 246, 254, 256, 264, 303, 307, 313, 319, 321, 329, 331, 339, 341, 349, 351, 359, 361, 369, 371, 379, 381, 389, 391, 399, 401, 409, 411, 419, 421, 429, 431, 439, 441, 638

Offset: 1

Author

Neville Holmes, Jun 08 2018

Keywords

• nonn
• base
• easy

Examples

			For k = 11, k^2 = 121;
for k = 26, k^2 = 676.
		

Crossrefs

Cf. A227858, A116499, A116501.

Cf. A123912, A186438.

Programs

Mathematica

Select[Range[638], (d = IntegerDigits[#^2]; d[[1]] == d[[-1]]) &] (* Giovanni Resta, Jun 25 2018 *)

PARI

for(n=1, 10^3, my(d=digits(n^2)); if( d[1]==d[#d], print1(n,", "))); \\ Joerg Arndt, Jun 10 2018

Python

def ok(n): s = str(n*n); return s[0] == s[-1]
print(list(filter(ok, range(1, 639)))) # Michael S. Branicky, Jul 16 2021