Triangular numbers n such that sigma(n) is a square number.

Terms

a(0) =1a(1) =3a(2) =66a(3) =210a(4) =820a(5) =2346a(6) =4278a(7) =22578a(8) =27966a(9) =32131a(10) =35511a(11) =51681a(12) =53956a(13) =102378a(14) =169653a(15) =173755a(16) =177906a(17) =223446a(18) =241860a(19) =256686a(20) =306153a(21) =310866a(22) =349866a(23) =431056a(24) =434778a(25) =470935a(26) =491536a(27) =512578a(28) =567645a(29) =579426