A030481 Squares of primes, with property that all even digits occur together and all odd digits occur together.

4, 9, 25, 49, 289, 841, 2209, 2809, 4489, 6241, 6889, 22201, 22801, 24649, 66049, 80089, 208849, 426409, 466489, 822649, 2042041, 2468041, 2866249, 2886601, 4068289, 6046681, 6086089, 6466849, 6806881, 6848689, 8082649, 8288641, 8462281, 8826841, 22648081, 26020201, 26822041, 28440889, 44262409

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Comments

Since the 10's digit of any odd square is even, all digits except the last must be even. - Robert Israel, Jan 04 2024

Links

• Robert Israel, Table of n, a(n) for n = 1..3000

Crossrefs

Includes (2*10^(2k) + 2*10^k + 1)^2 for k in A296444.

Programs

Maple

filter:= proc(n) local L;
  convert(convert(floor(n/10),base,10),set) mod 2 = {0}
end proc:
[4, 9, op(select(filter, [seq(ithprime(i)^2, i=3..20000)]))]; # Robert Israel, Jan 04 2024

Extensions

More terms from Robert Israel, Jan 04 2024