A389573 a(n) = Sum_{k=1..floor((n+1)/2)} A389524(n, n - 2*k + 2).

1, 2, 3, 4, 3, 4, 5, 7, 4, 4, 7, 9, 3, 6, 10, 9, 5, 6, 7, 13, 6, 4, 13, 14, 4, 8, 10, 11, 7, 8, 13, 16, 6, 6, 14, 17, 3, 8, 18, 14, 9, 8, 7, 21, 9, 6, 21, 19, 6, 10, 14, 13, 7, 12, 18, 24, 6, 4, 19, 22, 7, 10, 23, 18, 10, 12, 7, 23, 10, 8, 29, 21, 5, 12, 17, 21, 10, 8

Offset

1,2

Links

Table of n, a(n) for n=1..78.

Mathematica

Clear[t]; t[n_, 1] = If[n == 1, 1, 0]; t[n_, k_] := t[n, k] = If[n >= k, (1 + Sum[t[n - i, k - 1], {i, 1, k - 1}] -Sum[t[n - i, k], {i, 1, n - 1}]), 0]; ParallelTable[Sum[t[n, n - 2*k + 2], {k, 1, Floor[(n + 1)/2]}], {n, 1, 78}]

Prog

(PARI) a(n) = my(m=tabl(n)); sum(k=1, n, if (!((n-k)%2), m[n, k])); \\ Michel Marcus, Oct 16 2025

Crossrefs

Cf. A389524, A000005, A387793, A389526.

Cf. A025052 (fixed points).

Sequence in context: A309241 A065651 A322567 * A349049 A221356 A177329

Adjacent sequences: A389570 A389571 A389572 * A389574 A389575 A389576

Keyword

nonn

Author

Mats Granvik, Oct 08 2025

Status

approved