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

1,1

Comments

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

Links

Table of n, a(n) for n=1..10.

Erich Friedman, Problem of the month October 2011

Example

     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).

Crossrefs

Subsequence of A364151 (more than 2 factors allowed).

Cf. A188630 (analog for triangular numbers).

Sequence in context: A104591 A318119 A364151 * A171347 A193171 A013487

Adjacent sequences: A196565 A196566 A196567 * A196569 A196570 A196571

Keyword

nonn,more

Author

Kausthub Gudipati, Oct 04 2011

Extensions

Name clarified by Pontus von Brömssen, Jun 22 2023

Status

approved