Positive integers a such that f(3a)+f(a)=concatenation of 3a and a, where f(k)=k(k+3)/2 (A000096).

A099151

Positive integers a such that f(3a)+f(a)=concatenation of 3a and a, where f(k)=k(k+3)/2 (A000096).

Terms

    a(0) =5a(1) =59a(2) =599a(3) =5999a(4) =59999a(5) =599999a(6) =5999999a(7) =59999999a(8) =599999999a(9) =5999999999a(10) =59999999999a(11) =599999999999

External references