A088938 Occurrences of 2's in A088936.

2, 3, 5, 10, 27, 104, 541, 3498, 26615, 231172, 2250129, 24227486, 285705643, 3660694200, 50624828357, 751426146514, 11913622408671, 200919532718828, 3591112295892985, 67803855263483142, 1348467602319393299, 28174602435230023456, 617001101156944493613, 14131835969321147283770

Offset

1,1

Links

Table of n, a(n) for n=1..24.

Formula

a(n) = 2 + (1/2)*Sum_{k=1..n-1} Sum_{i=0..k} i!. - Benoit Cloitre and Claude Lenormand

Mathematica

a[n_] := 2 + Sum[i!, {k, 1, n-1}, {i, 0, k}]/2; Array[a, 30] (* Amiram Eldar, Jan 12 2025 *)

Crossrefs

Cf. A088936, A088937, A088939, A088940.

Sequence in context: A204518 A336991 A223545 * A000617 A132183 A259878

Adjacent sequences: A088935 A088936 A088937 * A088939 A088940 A088941

Keyword

nonn

Author

Benoit Cloitre, Oct 25 2003

Status

approved