Number of sets of exactly four positive integers <= n having a square element sum.

Terms

a(0) =0a(1) =0a(2) =2a(3) =5a(4) =8a(5) =14a(6) =23a(7) =34a(8) =49a(9) =69a(10) =93a(11) =123a(12) =160a(13) =204a(14) =255a(15) =315a(16) =383a(17) =462a(18) =554a(19) =658a(20) =775a(21) =904a(22) =1046a(23) =1205a(24) =1384a(25) =1581a(26) =1797a(27) =2031a(28) =2282a(29) =2556