Infinite sum of the odd numbers, compacted (see the Comments line for an explanation).

Terms

a(0) =4a(1) =12a(2) =20a(3) =28a(4) =57a(5) =203a(6) =76a(7) =129a(8) =371a(9) =124a(10) =201a(11) =219a(12) =237a(13) =623a(14) =505a(15) =327a(16) =2489a(17) =1099a(18) =332a(19) =865a(20) =543a(21) =1337a(22) =2743a(23) =452a(24) =1165a(25) =723a(26) =1757a(27) =1315a(28) =813a(29) =831