A196568 Binomial coefficients of the form C(k, 3) that are products of two other binomial coefficients of the form C(k, 3).

560, 19600, 43680, 893200, 1521520, 7207200, 29269240, 2845642800, 26595476600, 249466897680

Offset: 1

Author

Kausthub Gudipati, Oct 04 2011

Keywords

• nonn
• more

Comments

a(11), if it exists, > C(5*10^6, 3). - D. S. McNeil, Oct 26 2011

Examples

			     560 = C( 16, 3) = C( 8, 3) * C( 5, 3);
   19600 = C( 50, 3) = C(16, 3) * C( 7, 3);
   43680 = C( 65, 3) = C(14, 3) * C(10, 3);
  893200 = C(176, 3) = C(30, 3) * C(12, 3).
		

Links

• Erich Friedman, Problem of the month October 2011

Crossrefs

Subsequence of A364151 (more than 2 factors allowed).

Cf. A188630 (analog for triangular numbers).

Extensions

Name clarified by Pontus von Brömssen, Jun 22 2023