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.

A140643 First differences of A140642.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 2, 1, 1, 4, 4, 1, 1, 2, 8, 8, 2, 1, 1, 4, 16, 16, 4, 1, 1, 2, 8, 32, 32, 8, 2, 1, 1, 4, 16, 64, 64, 16, 4, 1
Offset: 0

Views

Author

Paul Curtz, Jul 08 2008

Keywords

Comments

(*) Main diagonal = A011782 but vertical = 1, A011782 unknown.

Programs

  • Mathematica
    maxTerm = 384; FixedPoint[(nMax++; Print["nMax = ", nMax]; jj = Table[(2^n - (-1)^n)/3, {n, 0, nMax}]; Table[Differences[jj, n], {n, 0, nMax}] // Flatten // Abs // Union // Select[#, 0 < # <= maxTerm &] &) &, nMax = 5 ] // Differences (* Jean-François Alcover, Dec 16 2014 *)

Formula

Also a triangle on line (*): 1; 1, 1; 1, 1, 2; 2, 1, 1, 4; 4, 1, 1, 2, 8; 8, 2, 1, 1, 4, 16; 16, 4, 1, 1, 2, 8, 32; 32, 8, 2, 1, 1, 4, 16, 64; Row sums:1, 2, 4, 8, 16 =A000079(n). Note even palindromes finishing a row and beginning next one.

A140648 Triangle T(n,m) which can create A140642 without help of Jacobsthal numbers.

Original entry on oeis.org

1, 2, 0, 4, 1, 0, 8, 2, 0, 1, 16, 4, 1, 0, 2, 32, 8, 2, 0, 1, 4, 64, 16, 4, 1, 0, 2, 8, 128, 32, 8, 2, 0, 1, 4, 16, 256, 64, 16, 4, 1, 0, 2, 8, 32, 512, 128, 32, 8, 2, 0, 1, 4, 16, 64
Offset: 0

Views

Author

Paul Curtz, Jul 09 2008

Keywords

Comments

This triangle T(.,.) provides the additional terms if A140642 is constructed with a Pascal-type recurrence: A140642(n+1,m+1) = A140642(n,m) + A140642(n,m+1) + T(n,m+1).
Note almost odd palindromes (of squares) followed by their double.
Examples: 40=16+20+4, 42=20+21+1, 43=21+22+0, 44=22+24+2.

Examples

			Triangle begins:
    1;
    2,  0;
    4,  1,  0;
    8,  2,  0,  1;
   16,  4,  1,  0,  2;
   32,  8,  2,  0,  1,  4;
   64, 16,  4,  1,  0,  2,  8;
  128, 32,  8,  2,  0,  1,  4, 16;
		

Crossrefs

Cf. A083329 (row sums).

Formula

Southeast diagonals based on A131577 (which is also in A140531). First preceded with 1, 0. Second with 2, 1, 0. Tends towards even palindromes, second part being A131577. Verticals: A000079, A131577, (0, A131577), ... .

A140951 Based on Jacobsthal numbers. Increasing order of different positive terms of A140950.

Original entry on oeis.org

1, 3, 5, 6, 10, 11, 12, 20, 21, 22, 24, 40, 42, 43, 44, 48, 80, 84, 85, 86, 88, 96, 160, 168, 170, 171, 172, 176, 192, 320, 336, 340, 341, 342, 344, 352, 384, 640
Offset: 0

Views

Author

Paul Curtz, Jul 25 2008

Keywords

Comments

Two possibilities of triangle on line. 1) From 1: 1; 3, 5; 6, 10, 11; 12, 20, 21, 22; 24, 40, 42, 43, 44; . 2) After 1: 3; 5, 6; 10, 11, 12; 20, 21, 22, 24; .

Formula

Also A140642 (1, 2, 3, 4, 5, 6, 8, 10, 11, 12, 16, 20) without A000079(n+1). Note position of A001045(n+2) terms: 0, 1, 2, 5, 8, 13 =A000982. See A140503 square .
Showing 1-3 of 3 results.