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 1-2 of 2 results.

A098355 Multiplication table of the powers of three read by antidiagonals.

Original entry on oeis.org

1, 3, 3, 9, 9, 9, 27, 27, 27, 27, 81, 81, 81, 81, 81, 243, 243, 243, 243, 243, 243, 729, 729, 729, 729, 729, 729, 729, 2187, 2187, 2187, 2187, 2187, 2187, 2187, 2187, 6561, 6561, 6561, 6561, 6561, 6561, 6561, 6561, 6561, 19683, 19683, 19683, 19683, 19683, 19683
Offset: 0

Views

Author

Douglas Stones (dssto1(AT)student.monash.edu.au), Sep 04 2004

Keywords

Comments

3^A003056: 3^n appears n+1 times.

Examples

			1; 3,3; 9,9,9; 27,27,27,27;
		

Crossrefs

Programs

  • Mathematica
    Flatten[Table[3^x, {x, 0, 13}, {y, 0, x}]] (* Alonso del Arte, Nov 29 2011 *)

A140503 Triangle T(d,n) read by rows, the n-th term of the d-th differences of the Jacobsthal sequence A001045.

Original entry on oeis.org

1, -1, 2, 3, -2, 4, -5, 6, -4, 8, 11, -10, 12, -8, 16, -21, 22, -20, 24, -16, 32, 43, -42, 44, -40, 48, -32, 64, -85, 86, -84, 88, -80, 96, -64, 128, 171, -170, 172, -168, 176, -160, 192, -128, 256, -341, 342, -340, 344, -336, 352, -320, 384, -256, 512, 683, -682, 684, -680
Offset: 1

Views

Author

Paul Curtz, Jun 30 2008

Keywords

Comments

If interpreted as a flat sequence a(j), we obtain a(j+1)-2a(j)= -3, 4, -1, -8, 8, -13, 16, -16, 16, -5, -32, 32, -32, 32, -53, 64, ... which is essentially the negative values of A096773 padded by groups of one, then two, then three etc. signed elements of A098354.

Examples

			A001045 and its d times iterated differences are
.0,.1,.1,.3,.5,11,21,43,...
.1,.0,.2,.2,.6,10,22,... < d=1
-1,.2,.0,.4,.4,12,... < d=2
.3,-2,.4,.0,.8,.. < d=3
-5,.6,-4,.8,.0,...
The sequence contains the first d elements of the d-th row, those up to the diagonal (which contains zeros).
		

Crossrefs

Cf. A001045, A140944 (with an extra diagonal of 0's).

Programs

  • PARI
    T(d,n) = (2^n - 2^d*(-1)^(d+n))/3 \\ Jianing Song, Aug 11 2022

Formula

T(d,n)=T(d-1,n+1)-T(d-1,n). T(0,n)=A001045(n).
Row sums: sum_{n=0..d-1} T(d,n) = A002450([(d+1)/2]).
Row sums of absolute values: sum_{n=0..d-1} |T(d,n)| = A045883(d).
T(d,n) = (2^n - 2^d*(-1)^(d+n))/3, for d > n >= 0. - Jianing Song, Aug 11 2022

Extensions

Edited by R. J. Mathar, Jul 14 2008
Showing 1-2 of 2 results.