A157908 Nonprimes whose digits are all square.

0, 1, 4, 9, 10, 14, 40, 44, 49, 90, 91, 94, 99, 100, 104, 110, 111, 114, 119, 140, 141, 144, 190, 194, 400, 404, 410, 411, 414, 440, 441, 444, 490, 494, 900, 901, 904, 909, 910, 914, 940, 944, 949, 990, 994, 999, 1000, 1001, 1004, 1010, 1011, 1014, 1040, 1041

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 09 2009

Keywords

• nonn
• base

Comments

Square digits are 0, 1, 4 or 9.

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000290, A141468.

Programs

Mathematica

Select[FromDigits/@Tuples[{0,1,4,9},4],!PrimeQ[#]&] (* Harvey P. Dale, Oct 14 2014 *)

Formula

a(n) = Theta(n^(log_4 10))

Extensions

Formula from Charles R Greathouse IV, Mar 25 2010