Fifth subdiagonal in array of n-gonal numbers A081422.

Terms

a(0) =1a(1) =7a(2) =24a(3) =58a(4) =115a(5) =201a(6) =322a(7) =484a(8) =693a(9) =955a(10) =1276a(11) =1662a(12) =2119a(13) =2653a(14) =3270a(15) =3976a(16) =4777a(17) =5679a(18) =6688a(19) =7810a(20) =9051a(21) =10417a(22) =11914a(23) =13548a(24) =15325a(25) =17251a(26) =19332a(27) =21574a(28) =23983a(29) =26565