Sum of previous term and preceding non-divisors.

Terms

a(0) =2a(1) =3a(2) =5a(3) =10a(4) =13a(5) =33a(6) =63a(7) =126a(8) =187a(9) =442a(10) =869a(11) =1753a(12) =3506a(13) =5257a(14) =12269a(15) =24538a(16) =36805a(17) =85876a(18) =171755a(19) =343507a(20) =687019a(21) =1374038a(22) =2061055a(23) =4809126a(24) =9618252a(25) =14427378a(26) =28854567a(27) =62518388a(28) =125036840a(29) =250073665