cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A278483 Transpose of square array A278482.

Original entry on oeis.org

0, 0, 1, 0, 2, 2, 0, 2, 4, 3, 0, 2, 6, 6, 4, 0, 2, 6, 8, 8, 5, 0, 2, 6, 12, 12, 10, 6, 0, 2, 6, 12, 14, 14, 12, 7, 0, 2, 6, 12, 18, 18, 18, 14, 8, 0, 2, 6, 12, 18, 24, 24, 20, 16, 9, 0, 2, 6, 12, 18, 26, 26, 26, 24, 18, 10, 0, 2, 6, 12, 18, 26, 30, 30, 30, 26, 20, 11, 0, 2, 6, 12, 18, 26, 38, 38, 38, 36, 30, 22, 12
Offset: 0

Views

Author

Antti Karttunen, Nov 23 2016

Keywords

Comments

See comments in A278482.

Crossrefs

Transpose: A278482.

Programs

A278484 Main diagonal of A278482.

Original entry on oeis.org

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

Views

Author

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

Keywords

Crossrefs

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]

A278492 Square array where row n (n >= 0) gives the numbers remaining after the n-th round of the Flavius sieve, read by descending antidiagonals.

Original entry on oeis.org

1, 2, 1, 3, 3, 1, 4, 5, 3, 1, 5, 7, 7, 3, 1, 6, 9, 9, 7, 3, 1, 7, 11, 13, 13, 7, 3, 1, 8, 13, 15, 15, 13, 7, 3, 1, 9, 15, 19, 19, 19, 13, 7, 3, 1, 10, 17, 21, 25, 25, 19, 13, 7, 3, 1, 11, 19, 25, 27, 27, 27, 19, 13, 7, 3, 1, 12, 21, 27, 31, 31, 31, 27, 19, 13, 7, 3, 1, 13, 23, 31, 37, 39, 39, 39, 27, 19, 13, 7, 3, 1
Offset: 0

Views

Author

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

Keywords

Comments

The terms of square array A(row,col) are read by descending antidiagonals as A(0,0), A(0,1), A(1,0), A(0,2), A(1,1), A(2,0), ...

Examples

			The top left corner of the array:
1, 2, 3,  4,  5,  6,  7,  8,  9, 10 (row 0: start from A000027)
1, 3, 5,  7,  9, 11, 13, 15, 17, 19 (after the 1st round, A005408 remain)
1, 3, 7,  9, 13, 15, 19, 21, 25, 27 (after the 2nd, A047241)
1, 3, 7, 13, 15, 19, 25, 27, 31, 37
1, 3, 7, 13, 19, 25, 27, 31, 39, 43
1, 3, 7, 13, 19, 27, 31, 39, 43, 49
1, 3, 7, 13, 19, 27, 39, 43, 49, 61
1, 3, 7, 13, 19, 27, 39, 49, 61, 63
1, 3, 7, 13, 19, 27, 39, 49, 63, 67
1, 3, 7, 13, 19, 27, 39, 49, 63, 79
		

Crossrefs

One more than A278482.
Transpose: A278493.
Main diagonal: A000960.
Cf. A278507 (the numbers removed at each round).
Similarly constructed arrays for other sieves: A258207, A260717.

Programs

Formula

A(n,k) = 1 + A278482(n,k).
Showing 1-3 of 3 results.