Squares of (odd numbers not divisible by 5).
1, 9, 49, 81, 121, 169, 289, 361, 441, 529, 729, 841, 961, 1089, 1369, 1521, 1681
1 seqfan posts
Wed Mar 3 19:14:04 CET 2010 [seqfan] Re: A169580 and Catalan's empirical claim that the triple of any odd square not divisible by 5 is a sum of squares of three primes other than 2 and 3.