A129960 a(n) = floor(sqrt(2*n!)).

1, 1, 2, 3, 6, 15, 37, 100, 283, 851, 2693, 8934, 30951, 111597, 417560, 1617203, 6468815, 26671611, 113158063, 493244564, 2205856753, 10108505544, 47413093714, 227385209452, 1113955476429, 5569777382145, 28400403557928, 147572825753377, 780881994429009

Offset

0,3

Comments

a(n) is the index of the closest triangular number to n!. - Ruediger Jehn, Nov 11 2020

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

Prog

(PARI) a(n)={sqrtint(2*n!)} \\ Andrew Howroyd, Jan 02 2020

Crossrefs

Cf. A000142, A338489.

Sequence in context: A237585 A147773 A006403 * A115098 A036418 A120589

Adjacent sequences: A129957 A129958 A129959 * A129961 A129962 A129963

Keyword

nonn,easy

Author

Roger L. Bagula, Jun 10 2007

Extensions

New name from Anthony Hernandez, Dec 28 2018

Terms a(21) and beyond from Andrew Howroyd, Jan 02 2020

Status

approved