A361506 a(n) = floor( (4/5)*( (9/4)^(n+1)-1 ) ).

1, 3, 8, 19, 45, 102, 232, 524, 1181, 2659, 5984, 13466, 30300, 68177, 153400, 345151, 776590, 1747330, 3931495, 8845865, 19903197, 44782195, 100759939, 226709865, 510097199, 1147718699, 2582367075, 5810325919, 13073233320, 29414774972, 66183243689, 148912298302

Offset

0,2

References

N. Tokuda, An Improved Shellsort, IFIP Transactions, A-12 (1992) 449-457.

Links

Table of n, a(n) for n=0..31.

Marcin Ciura, Best Increments for the Average Case of Shellsort, in R. Freivalds, (ed.), Fundamentals of Computation Theory: 13th International Symposium, FCT 2001, Riga, Latvia, August 2001, Lecture Notes in Computer Science, vol. 2138, Springer, pp. 106-117.

Mathematica

A361506[n_]:=Floor[4/5((9/4)^(n+1)-1)]; Array[A361506, 50, 0] (* Paolo Xausa, Dec 02 2023 *)

Crossrefs

Other sequences used for Shell sort: A003462, A033622, A036562, A036564, A036569, A055875, A055876, A108870, A361507.

Sequence in context: A077850 A097550 A079490 * A026789 A308372 A096576

Adjacent sequences: A361503 A361504 A361505 * A361507 A361508 A361509

Keyword

nonn

Author

N. J. A. Sloane, Mar 20 2023, at the suggestion of Don Knuth.

Extensions

Some terms corrected by Paolo Xausa, Dec 02 2023

Status

approved