A278484 Main diagonal of A278482.

0, 2, 6, 12, 18, 26, 38, 48, 62, 78, 90, 108, 132, 146, 180, 206, 222, 252, 288, 306, 348, 386, 398, 458, 480, 528, 566, 612, 648, 708, 762, 806, 842, 926, 948, 1008, 1092, 1110, 1188, 1260, 1320, 1358, 1470, 1482, 1578, 1692, 1718, 1806, 1898, 1932, 2022, 2160, 2186, 2268, 2366, 2478, 2532, 2702, 2738, 2798, 2966, 3018

Offset: 0

Author

Antti Karttunen, Nov 23 2016 after David W. Wilson's posting on SeqFan list Nov 22 2016

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..10000
• D. Wilson et al., Interesting sequence, SeqFan list, Nov. 2016
• Index entries for sequences generated by sieves

Crossrefs

Cf. A000960, A073359.

Main diagonal of A278482 (and A278483).

Partial sums of A278484.

Programs

Mathematica

a[n_]:= Fold[Floor@Times@##&,Prepend[Table[(k + 1)/k, {k, n, 1, -1}], n]] (* Ethan Beihl, Nov 29 2016 *)

Formula

By definition, a(n) = A278482(n,n).

a(n) = A000960(n + 1) - 1.

a(n) = 2*A073359(n). [Observed by Arie Groeneveld on SeqFan list, Nov 22 2016.] [Conjectural, true for n <= 2000 David W. Wilson, Nov 23 2016]