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.

A143593 Triangle read by rows, square of A238303 (an infinite lower triangular matrix with 1's in the first column and the rest 2's).

Original entry on oeis.org

1, 3, 4, 5, 8, 4, 7, 12, 8, 4, 9, 16, 12, 8, 4, 11, 20, 16, 12, 8, 4, 13, 24, 20, 16, 12, 8, 4, 15, 28, 24, 20, 16, 12, 8, 4, 17, 32, 28, 24, 20, 16, 12, 8, 4, 19, 36, 32, 28, 24, 20, 16, 12, 8, 4
Offset: 1

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Author

Keywords

Comments

Row sums = A056220 starting with offset 1: (1, 7, 17, 31, 49, 71, 97,...).

Examples

			The square of the infinite lower triangular matrix (1; 1,2; 1,2,2;...) =
1;
3, 4;
5, 8, 4;
7, 12, 8, 4;
9, 16, 12, 8, 4;
11, 20, 16, 12, 8, 4;
13, 24, 20, 16, 12, 8, 4;
...
		

Crossrefs

Formula

Triangle read by rows, square of an infinite lower triangular matrix with 1's in the first column and the rest 2's. Square of (A000012 * (S(k) * 0^(n-k)), 1<=k<=n

A238339 Square number array read by ascending antidiagonals: T(1,k) = 2*k + 1, and T(n,k) = (2*n^(k+1)-n-1)/(n-1) otherwise.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 5, 5, 1, 1, 7, 13, 7, 1, 1, 9, 25, 29, 9, 1, 1, 11, 41, 79, 61, 11, 1, 1, 13, 61, 169, 241, 125, 13, 1, 1, 15, 85, 311, 681, 727, 253, 15, 1, 1, 17, 113, 517, 1561, 2729, 2185, 509, 17, 1, 1, 19, 145, 799, 3109, 7811, 10921, 6559, 1021, 19, 1
Offset: 0

Views

Author

Philippe Deléham, Feb 24 2014

Keywords

Examples

			Square array begins:
1..1...1.....1......1.......1........1........1...
1..3...5.....7......9......11.......13.......15...
1..5..13....29.....61.....125......253......509...
1..7..25....79....241.....727.....2185.....6559...
1..9..41...169....681....2729....10921....43689...
1.11..61...311...1561....7811....39061...195311...
1.13..85...517...3109...18661...111973...671845...
1.15.113...799...5601...39215...274513..1921599...
1.17.145..1169...9361...74897...599185..4793489...
1.19.181..1639..14761..132859..1195741.10761679...
1.21.221..2221..22221..222221..2222221.22222221...
		

Crossrefs

Cf. A238303.

Programs

  • Maple
    T:= proc(n, k); if n=1 then 2*k+1 else (2*n^(k+1)-n-1)/(n-1) fi end:
    seq(seq(T(n-k, k), k=0..n), n=0..10); # Georg Fischer, Oct 14 2023

Formula

T(0,k) = A000012(k) = 1;
T(1,k) = A005408(k) = 2k+1;
T(2,k) = A036563(k+2);
T(3,k) = A058481(k+1);
T(4,k) = A083584(k);
T(5,k) = A137410(k);
T(6,k) = A233325(k);
T(7,k) = A233326(k);
T(8,k) = A233328(k);
T(9,k) = A211866(k+1);
T(10,k) = A165402(k+1);
T(n,0) = A000012(n) = 1;
T(n,1) = A005408(n) = 2*n+1;
T(n,2) = A001844(n) = 2*n^2 + 2*n + 1.

Extensions

Definition amended by Georg Fischer, Oct 14 2023

A247349 Regular triangle obtained by procedure described in comment in the case of m=3.

Original entry on oeis.org

1, 1, 2, 2, 1, 2, 2, 1, 2, 3, 3, 2, 1, 2, 3, 2, 3, 3, 2, 1, 4, 2, 1, 4, 2, 3, 3, 3, 2, 3, 3, 3, 2, 1, 4, 3, 3, 2, 1, 4, 3, 2, 3, 3, 3, 4, 3, 2, 3, 3, 3, 3, 2, 1, 4, 3, 3, 3, 3, 2, 1, 4, 4, 3, 2, 5, 3, 2, 1, 4, 4, 3, 2, 5, 3, 3, 3, 4, 4, 4, 3, 2, 5, 3, 3, 3, 4, 3, 2, 1, 4
Offset: 1

Views

Author

Michel Marcus, Sep 16 2014

Keywords

Comments

"Consider an array of numbers formed by a rotating queue: starting with just the number 1, to obtain the next row we move everything in the last row m steps to the left, with numbers at the front of the row cycling around and appearing at the back. We then append 1 plus the head of the last row to the new row." (from the Introduction of article by P. J. Graber).

Crossrefs

Cf. A238303 (triangle obtained when m=0).

Programs

  • PARI
    moveleft(v, m) = {va = v; for (i=1, m, nb = #va; vb = vector(nb, i, if (i
    				
Showing 1-3 of 3 results.