A305739 a(n) = n!*T(n) - 1, where T(n) is the n-th triangular number.

0, 5, 35, 239, 1799, 15119, 141119, 1451519, 16329599, 199583999, 2634508799, 37362124799, 566658892799, 9153720575999, 156920924159999, 2845499424767999, 54420176498687999, 1094805903679487999, 23112569077678079999, 510909421717094399999

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = n*(n+1)!/2 - 1. - Michel Marcus, Jun 23 2018

a(n) = A180119(n)-1 = A001286(n+1)-1. - Alois P. Heinz, Jun 24 2018

Maple

seq(n*(n+1)!/2-1, n=1..21);

Prog

(PARI) a(n) = n*(n+1)!/2 - 1; \\ Michel Marcus, Jun 23 2018

Crossrefs

Cf. A000142, A000217, A001286, A180119.

See A305738 for the indices of primes in this sequence.

Sequence in context: A154780 A007995 A091928 * A290903 A155127 A239846

Adjacent sequences: A305736 A305737 A305738 * A305740 A305741 A305742

Keyword

nonn

Author

Maheswara Rao Valluri, Jun 22 2018

Status

approved