A033618 - OEIS

%I #13 Jul 06 2024 11:54:31

%S 2,2,2,2,3,2,2,3,2,3,3,2,4,5,2,3,3,4,3,4,3,4,5,3,3,3,3,2,3,3,3,6,3,2,

%T 3,2,3,3,3,3,4,2,3,3,7,3,4,3,4,5,4,3,4,2,2,3,3,3,4,3,3,3,3,4,3,2,3,6,

%U 2,3,3

%N Number of ways n-th repdigit number, A010785(n), can be expressed as a polygonal number.

%H M. Keith, <a href="http://www.cs.uwaterloo.ca/journals/JIS/keith.html">On Repdigit Polygonal Numbers</a>, J. Integer Sequences, Vol. 1, 1998, #6.

%e The n-th k-sided polygonal number is P(n,k)=n((k-2)n+4-k)/2 (k >= 2, n >= 1). For each repdigit number R>=2, sequence gives number of (n,k) such that P(n,k)=R.

%K nonn,base

%O 2,1

%A _Mike Keith_