a(n) is the smallest number which is the sum of two positive n-gonal numbers in more than one way.

Terms

a(0) =16a(1) =50a(2) =211a(3) =384a(4) =470a(5) =1053a(6) =1500a(7) =2242a(8) =3197a(9) =3277a(10) =5501a(11) =6780a(12) =8710a(13) =9896a(14) =10584a(15) =15198a(16) =15395a(17) =21237a(18) =23346a(19) =28696a(20) =33596a(21) =37725a(22) =40795a(23) =48474a(24) =55369a(25) =54146a(26) =69113a(27) =75732a(28) =84962a(29) =92541