Triangular numbers in A062918.

Terms

a(0) =1a(1) =3a(2) =6a(3) =10a(4) =15a(5) =21a(6) =28a(7) =36a(8) =45a(9) =78a(10) =3741a(11) =4005a(12) =4278a(13) =14028a(14) =224115a(15) =238395a(16) =258121a(17) =994755a(18) =1104841a(19) =2440945a(20) =4601061a(21) =19185915a(22) =26451901a(23) =27073761a(24) =38250631a(25) =611712753a(26) =1787631321a(27) =3620877351a(28) =4427640253a(29) =16786524835