Number of nonempty subsets of {1..n} whose elements have a square average.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =10a(6) =20a(7) =26a(8) =31a(9) =35a(10) =41a(11) =63a(12) =143a(13) =399a(14) =1083a(15) =2554a(16) =5078a(17) =8596a(18) =12772a(19) =17222a(20) =21792a(21) =27126a(22) =36538a(23) =62530a(24) =146701a(25) =412191a(26) =1178071a(27) =3156949a(28) =7703823a(29) =16992539