Pentagonal numbers > 0 which are not the difference of two other pentagonal numbers > 0.

Terms

a(0) =1a(1) =5a(2) =12a(3) =51a(4) =92a(5) =117a(6) =176a(7) =330a(8) =477a(9) =852a(10) =1080a(11) =4347a(12) =9801a(13) =13776a(14) =24512a(15) =27270a(16) =39285a(17) =69876a(18) =88452a(19) =124272a(20) =137562a(21) =220992a(22) =268182a(23) =315792a(24) =354051a(25) =403782a(26) =523626a(27) =612162a(28) =629532a(29) =699392