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 A033618 Number of ways n-th repdigit number, A010785(n), can be expressed as a polygonal number. 0
 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, 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, 2, 3, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Table of n, a(n) for n=2..72. M. Keith, On Repdigit Polygonal Numbers, J. Integer Sequences, Vol. 1, 1998, #6. EXAMPLE 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. CROSSREFS Sequence in context: A234092 A047931 A258571 * A061357 A270966 A138139 Adjacent sequences: A033615 A033616 A033617 * A033619 A033620 A033621 KEYWORD nonn,base AUTHOR Mike Keith (domnei(AT)aol.com) STATUS approved

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Last modified September 30 07:44 EDT 2023. Contains 365781 sequences. (Running on oeis4.)