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

Terms

a(0) =1a(1) =5a(2) =12a(3) =35a(4) =51a(5) =92a(6) =117a(7) =176a(8) =330a(9) =477a(10) =782a(11) =852a(12) =1080a(13) =3876a(14) =4347a(15) =7526a(16) =7740a(17) =9801a(18) =13776a(19) =14652a(20) =22632a(21) =24512a(22) =27270a(23) =39285a(24) =69876a(25) =85562a(26) =88452a(27) =103622a(28) =124272a(29) =137562