(A001147(n+1)-1)/2, equals the index of A249348(n) within the triangular numbers A000217.

A249349

(A001147(n+1)-1)/2, equals the index of A249348(n) within the triangular numbers A000217.

Terms

    a(0) =0a(1) =1a(2) =7a(3) =52a(4) =472a(5) =5197a(6) =67567a(7) =1013512a(8) =17229712a(9) =327364537a(10) =6874655287a(11) =158117071612

External references