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 1-4 of 4 results.

A358296 Row 3 of the array in A115009.

Original entry on oeis.org

2, 13, 28, 49, 74, 105, 140, 181, 226, 277, 332, 393, 458, 529, 604, 685, 770, 861, 956, 1057, 1162, 1273, 1388, 1509, 1634, 1765, 1900, 2041, 2186, 2337, 2492, 2653, 2818, 2989, 3164, 3345, 3530, 3721, 3916, 4117, 4322, 4533, 4748, 4969, 5194, 5425, 5660, 5901, 6146, 6397, 6652, 6913, 7178, 7449, 7724, 8005, 8290, 8581, 8876, 9177
Offset: 1

Views

Author

N. J. A. Sloane, Dec 05 2022

Keywords

Comments

The second differences are 4,6,4,6,4,6,...

Crossrefs

Cf. A115009.

A358297 Bisection of main diagonal of A115009.

Original entry on oeis.org

6, 86, 418, 1282, 3106, 6394, 11822, 20074, 32086, 48934, 71554, 101250, 139350, 187254, 246690, 319346, 407302, 511714, 634726, 779074, 946622, 1140238, 1362082, 1614994, 1901930, 2224654, 2587402, 2992414, 3441754, 3941074, 4493414, 5102618, 5770646, 6501286, 7300578, 8170130, 9117486, 10145578, 11256062, 12454678, 13746910, 15140014, 16634530
Offset: 1

Views

Author

N. J. A. Sloane, Dec 05 2022

Keywords

References

  • D. M. Acketa, J. D. Zunic: On the number of linear partitions of the (m,n)-grid. Inform. Process. Lett., 38 (3) (1991), 163-168. See Table A.1.
  • Jovisa Zunic, Note on the number of two-dimensional threshold functions, SIAM J. Discrete Math. Vol. 25 (2011), No. 3, pp. 1266-1268. See Equation (1.2).

Crossrefs

Cf. A114043, A115009, A141255, 33351.

A332351 Triangle read by rows: T(m,n) = Sum_{-m= n >= 1.

Original entry on oeis.org

0, 1, 6, 2, 13, 28, 3, 22, 49, 86, 4, 33, 74, 131, 200, 5, 46, 105, 188, 289, 418, 6, 61, 140, 251, 386, 559, 748, 7, 78, 181, 326, 503, 730, 979, 1282, 8, 97, 226, 409, 632, 919, 1234, 1617, 2040, 9, 118, 277, 502, 777, 1132, 1521, 1994, 2517, 3106, 10, 141, 332, 603, 934, 1361, 1828, 2397, 3026, 3735, 4492
Offset: 1

Views

Author

N. J. A. Sloane, Feb 10 2020

Keywords

Comments

This is the triangle in A332350, halved.
This triangle is the lower half of the array defined in A115009.

Examples

			Triangle begins:
0,
1, 6,
2, 13, 28,
3, 22, 49, 86,
4, 33, 74, 131, 200,
5, 46, 105, 188, 289, 418,
6, 61, 140, 251, 386, 559, 748,
7, 78, 181, 326, 503, 730, 979, 1282,
8, 97, 226, 409, 632, 919, 1234, 1617, 2040,
9, 118, 277, 502, 777, 1132, 1521, 1994, 2517, 3106,
...
		

References

  • Jovisa Zunic, Note on the number of two-dimensional threshold functions, SIAM J. Discrete Math. Vol. 25 (2011), No. 3, pp. 1266-1268. See Equation (1.2).

Crossrefs

The main diagonal is A141255, or A114043 - 1.
This is the lower triangle of the array in A115009.

Programs

  • Maple
    VR := proc(m,n,q) local a,i,j; a:=0;
    for i from -m+1 to m-1 do for j from -n+1 to n-1 do
    if gcd(i,j)=q then a:=a+(m-abs(i))*(n-abs(j)); fi; od: od: a; end;
    for m from 1 to 12 do lprint(seq(VR(m,n,1)/2,n=1..m),); od:
  • Mathematica
    A332351[m_,n_]:=Sum[If[CoprimeQ[i,j],2(m-i)(n-j),0],{i,m-1},{j,n-1}]+2m*n-m-n;Table[A332351[m,n],{m,15},{n,m}] (* Paolo Xausa, Oct 18 2023 *)

A115011 Array read by antidiagonals: let V(m,n) = Sum_{i=1..m, j=1..n, gcd(i,j)=1} (m+1-i)*(n+1-j), then T(m,n) = 2*(2*m*n+m+n+2*V(m,n)), for m >= 0, n >= 0.

Original entry on oeis.org

0, 2, 2, 4, 12, 4, 6, 26, 26, 6, 8, 44, 56, 44, 8, 10, 66, 98, 98, 66, 10, 12, 92, 148, 172, 148, 92, 12, 14, 122, 210, 262, 262, 210, 122, 14, 16, 156, 280, 376, 400, 376, 280, 156, 16, 18, 194, 362, 502, 578, 578, 502, 362, 194, 18, 20, 236, 452, 652, 772, 836, 772, 652, 452, 236, 20
Offset: 0

Views

Author

N. J. A. Sloane, Feb 24 2006

Keywords

Crossrefs

Twice A115009, which see for further information.

Programs

  • Mathematica
    V[m_, n_] := Sum[If[GCD[i, j] == 1, (m-i+1)(n-j+1), 0], {i, m}, {j, n}];
    T[m_, n_] := 2(2m n + m + n + 2 V[m, n]);
    Table[T[m-n, n], {m, 0, 10}, {n, 0, m}] // Flatten (* Jean-François Alcover, Oct 08 2018 *)
Showing 1-4 of 4 results.