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 1-10 of 12 results. Next

A159797 Triangle read by rows in which row n lists n+1 terms, starting with n, such that the difference between successive terms is equal to n-1.

Original entry on oeis.org

0, 1, 1, 2, 3, 4, 3, 5, 7, 9, 4, 7, 10, 13, 16, 5, 9, 13, 17, 21, 25, 6, 11, 16, 21, 26, 31, 36, 7, 13, 19, 25, 31, 37, 43, 49, 8, 15, 22, 29, 36, 43, 50, 57, 64, 9, 17, 25, 33, 41, 49, 57, 65, 73, 81, 10, 19, 28, 37, 46, 55, 64, 73, 82, 91, 100, 11, 21, 31, 41, 51, 61, 71, 81, 91, 101
Offset: 0

Views

Author

Omar E. Pol, Jul 09 2009

Keywords

Comments

Note that the last term of the n-th row is the n-th square A000290(n).
See also A162611, A162614 and A162622.
The triangle sums, see A180662 for their definitions, link the triangle A159797 with eleven sequences, see the crossrefs. - Johannes W. Meijer, May 20 2011
T(n,k) is the number of distinct sums in the direct sum of {1, 2, ... n} with itself k times for 1 <= k <= n+1, e.g., T(5,3) = the number of distinct sums in the direct sum {1,2,3,4,5} + {1,2,3,4,5} + {1,2,3,4,5}. The sums range from 1+1+1=3 to 5+5+5=15. So there are 13 distinct sums. - Derek Orr, Nov 26 2014

Examples

			Triangle begins:
0;
1, 1;
2, 3, 4;
3, 5, 7, 9;
4, 7,10,13,16;
5, 9,13,17,21,25;
6,11,16,21,26,31,36;
		

Crossrefs

Cf.: A006002 (row sums). - R. J. Mathar, Jul 17 2009
Cf. A163282, A163283, A163284, A163285. - Omar E. Pol, Nov 18 2009
From Johannes W. Meijer, May 20 2011: (Start)
Triangle sums (see the comments): A006002 (Row1), A050187 (Row2), A058187 (Related to Kn11, Kn12, Kn13, Fi1 and Ze1), A006918 (Related to Kn21, Kn22, Kn23, Fi2 and Ze2), A000330 (Kn3), A016061 (Kn4), A190717 (Related to Ca1 and Ze3), A144677 (Related to Ca2 and Ze4), A000292 (Related to Ca3, Ca4, Gi3 and Gi4) A190718 (Related to Gi1) and A144678 (Related to Gi2). (End)

Programs

Formula

Given m = floor( (sqrt(8*n+1)-1)/2 ), then a(n) = m + (n - m*(m+1)/2)*(m-1). - Carl R. White, Jul 24 2010

Extensions

Edited by Omar E. Pol, Jul 18 2009
More terms from Omar E. Pol, Nov 18 2009
More terms from Carl R. White, Jul 24 2010

A162610 Triangle read by rows in which row n lists n terms, starting with 2n-1, with gaps = n-1 between successive terms.

Original entry on oeis.org

1, 3, 4, 5, 7, 9, 7, 10, 13, 16, 9, 13, 17, 21, 25, 11, 16, 21, 26, 31, 36, 13, 19, 25, 31, 37, 43, 49, 15, 22, 29, 36, 43, 50, 57, 64, 17, 25, 33, 41, 49, 57, 65, 73, 81, 19, 28, 37, 46, 55, 64, 73, 82, 91, 100, 21, 31, 41, 51, 61, 71, 81, 91, 101, 111, 121
Offset: 1

Views

Author

Omar E. Pol, Jul 09 2009

Keywords

Comments

Note that the last term of the n-th row is the n-th square A000290(n).
Row sums are n*(n^2+2*n-1)/2, apparently in A127736. - R. J. Mathar, Jul 20 2009

Examples

			Triangle begins:
1
3, 4
5, 7, 9
7, 10, 13, 16
9, 13, 17, 21, 25
11, 16, 21, 26, 31, 36
		

Crossrefs

Cf. A209297; A005408 (left edge), A000290 (right edge), A127736 (row sums), A056220 (central terms), A026741 (number of odd terms per row), A142150 (number of even terms per row), A221491 (number of primes per row).

Programs

  • Haskell
    a162610 n k = k * n - k + n
    a162610_row n = map (a162610 n) [1..n]
    a162610_tabl = map a162610_row [1..]
    -- Reinhard Zumkeller, Jan 19 2013
  • Mathematica
    Flatten[Table[NestList[#+n-1&,2n-1,n-1], {n,15}]] (* Harvey P. Dale, Oct 20 2011 *)
  • Python
    # From R. J. Mathar, Oct 20 2009
    def A162610(n, k):
        return 2*n-1+(k-1)*(n-1)
    print([A162610(n,k) for n in range(1,20) for k in range(1,n+1)])
    

Formula

T(n,k) = n+k*n-k, 1<=k<=n. - R. J. Mathar, Oct 20 2009
T(n,k) = (k+1)*(n-1)+1. - Reinhard Zumkeller, Jan 19 2013

Extensions

More terms from R. J. Mathar, Oct 20 2009

A162609 Triangle read by rows in which row n lists n terms, starting with 1, with gaps = n-2 between successive terms.

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 1, 3, 5, 7, 1, 4, 7, 10, 13, 1, 5, 9, 13, 17, 21, 1, 6, 11, 16, 21, 26, 31, 1, 7, 13, 19, 25, 31, 37, 43, 1, 8, 15, 22, 29, 36, 43, 50, 57, 1, 9, 17, 25, 33, 41, 49, 57, 65, 73, 1, 10, 19, 28, 37, 46, 55, 64, 73, 82, 91, 1, 11, 21, 31, 41, 51, 61, 71, 81
Offset: 1

Views

Author

Omar E. Pol, Jul 09 2009

Keywords

Comments

Equals A081493 when first column is removed. - Georg Fischer, Jul 25 2023

Examples

			Triangle begins:
  1;
  1,  1;
  1,  2,  3;
  1,  3,  5,  7;
  1,  4,  7, 10, 13;
  1,  5,  9, 13, 17, 21;
  1,  6, 11, 16, 21, 26, 31;
		

Crossrefs

Cf. A060354 (row sums), A081493 (without first column).

Programs

  • Mathematica
    Table[NestList[#+(n-2)&,1,n-1],{n,20}]//Flatten (* Harvey P. Dale, Oct 23 2017 *)

Formula

T(n,n) = A002061(n-1).
T(n,k) = A076110(n-1,k) = 1+(n-2)*(k-1). - R. J. Mathar, Mar 30 2023

A162612 Triangle read by rows in which row n lists n terms, starting with n^2+n-1, with gaps = n^2-1 between successive terms.

Original entry on oeis.org

1, 5, 8, 11, 19, 27, 19, 34, 49, 64, 29, 53, 77, 101, 125, 41, 76, 111, 146, 181, 216, 55, 103, 151, 199, 247, 295, 343, 71, 134, 197, 260, 323, 386, 449, 512, 89, 169, 249, 329, 409, 489, 569, 649, 729, 109, 208, 307, 406, 505, 604, 703, 802, 901, 1000, 131, 251
Offset: 1

Views

Author

Omar E. Pol, Jul 09 2009

Keywords

Comments

Note that the last term of the n-th row is the n-th cube A000578(n).

Examples

			Triangle begins:
   1;
   5,   8;
  11,  19,  27;
  19,  34,  49,  64;
  29,  53,  77, 101, 125;
  41,  76, 111, 146, 181, 216;
		

Crossrefs

Programs

Formula

Sum_{k=1..n} T(n,k)= n*(n^3 + n^2 + n - 1)/2 (row sums). - R. J. Mathar, Jul 20 2009

Extensions

More terms from Franklin T. Adams-Watters, Aug 06 2009

A162613 Triangle read by rows in which row n lists n terms, starting with n, with gaps = n^2-1 between successive terms.

Original entry on oeis.org

1, 2, 5, 3, 11, 19, 4, 19, 34, 49, 5, 29, 53, 77, 101, 6, 41, 76, 111, 146, 181, 7, 55, 103, 151, 199, 247, 295, 8, 71, 134, 197, 260, 323, 386, 449, 9, 89, 169, 249, 329, 409, 489, 569, 649, 10, 109, 208, 307, 406, 505, 604, 703, 802, 901, 11, 131, 251, 371, 491, 611
Offset: 1

Views

Author

Omar E. Pol, Jul 09 2009

Keywords

Comments

Note that the last term of the n-th row is A100104(n).

Examples

			Triangle begins:
  1;
  2,   5;
  3,  11,  19;
  4,  19,  34,  49;
  5,  29,  53,  77, 101;
  6,  41,  76, 111, 146, 181;
		

Crossrefs

Cf. A100855 (row sums). - R. J. Mathar, Jul 20 2009

Programs

  • Mathematica
    Table[NestList[#+n^2-1&,n,n-1],{n,11}]//Flatten (* Harvey P. Dale, Feb 24 2016 *)

Extensions

More terms from Vincenzo Librandi, Aug 02 2010

A159788 a(n) = A159786(n+1)/2.

Original entry on oeis.org

0, 0, 2, 4, 4, 6, 16, 24, 24, 26, 32, 36, 38, 52, 88, 112, 112, 114, 120, 124, 126, 140, 168, 184, 186, 196, 212, 222, 240, 304, 432, 480, 480, 482, 488, 492, 494, 508, 536, 552, 554, 564, 580, 590, 608, 672, 768, 816, 818, 828
Offset: 0

Views

Author

Omar E. Pol, Apr 28 2009, May 02 2009

Keywords

Crossrefs

Toothpick sequence: A139250.

Extensions

a(11)-a(49) from Robert Price, May 10 2019

A162607 a(n) = n*(n^2 - 4*n + 5)/2.

Original entry on oeis.org

0, 1, 1, 3, 10, 25, 51, 91, 148, 225, 325, 451, 606, 793, 1015, 1275, 1576, 1921, 2313, 2755, 3250, 3801, 4411, 5083, 5820, 6625, 7501, 8451, 9478, 10585, 11775, 13051, 14416, 15873, 17425, 19075, 20826, 22681, 24643, 26715, 28900, 31201, 33621
Offset: 0

Views

Author

R. J. Mathar and Omar E. Pol, Jul 21 2009

Keywords

Comments

Positive values are the row sums of triangle A159798.

Crossrefs

Cf. A159798.

Programs

Formula

G.f.: x*(1 - 3*x + 5*x^2)/(1 - x)^4. - Vincenzo Librandi, Dec 19 2012
a(n) = A057145(n-1,n) = A072277(n-1). - R. J. Mathar, Jul 28 2016
E.g.f.: x*(x^2 - x + 2)*exp(x)/2. - G. C. Greubel, Apr 21 2018

A162619 Triangle read by rows in which row n lists n consecutive natural numbers A000027, starting with A014689(n) = A000040(n)-n.

Original entry on oeis.org

1, 1, 2, 2, 3, 4, 3, 4, 5, 6, 6, 7, 8, 9, 10, 7, 8, 9, 10, 11, 12, 10, 11, 12, 13, 14, 15, 16, 11, 12, 13, 14, 15, 16, 17, 18, 14, 15, 16, 17, 18, 19, 20, 21, 22, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 25, 26, 27, 28, 29, 30, 31, 32, 33
Offset: 1

Views

Author

Omar E. Pol, Jul 10 2009

Keywords

Comments

Note that the last term of the n-th row is A000040(n)-1 = A006093(n).
See also A162618 and A162620.

Examples

			Triangle begins:
.1;
.1, 2;
.2, 3, 4;
.3, 4, 5, 6;
.6, 7, 8, 9,10;
.7, 8, 9,10,11,12;
10,11,12,13,14,15,16;
11,12,13,14,15,16,17,18;
14,15,16,17,18,19,20,21,22;
19,20,21,22,23,24,25,26,27,28;
20,21,22,23,24,25,26,27,28,29,30;
		

Crossrefs

A162618 Triangle read by rows in which row n lists n consecutive natural numbers A000027, starting with A008578(n-1) - n + 1.

Original entry on oeis.org

1, 1, 2, 1, 2, 3, 2, 3, 4, 5, 3, 4, 5, 6, 7, 6, 7, 8, 9, 10, 11, 7, 8, 9, 10, 11, 12, 13, 10, 11, 12, 13, 14, 15, 16, 17, 11, 12, 13, 14, 15, 16, 17, 18, 19, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
Offset: 1

Views

Author

Omar E. Pol, Jul 10 2009

Keywords

Comments

Note that the last term of the n-th row is the noncomposite number A008578(n-1).

Examples

			Contribution from _Omar E. Pol_, Jul 15 2009: (Start)
Triangle begins:
   1;
   1,  2;
   1,  2,  3;
   2,  3,  4,  5;
   3,  4,  5,  6,  7;
   6,  7,  8,  9, 10, 11;
   7,  8,  9, 10, 11, 12, 13;
  10, 11, 12, 13, 14, 15, 16, 17;
  11, 12, 13, 14, 15, 16, 17, 18, 19;
  14, 15, 16, 17, 18, 19, 20, 21, 22, 23;
  19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29;
  20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31;
(End)
		

Crossrefs

A162620 Triangle read by rows in which row n lists n consecutive natural numbers A000027, starting with A000040(n)-n+1.

Original entry on oeis.org

2, 2, 3, 3, 4, 5, 4, 5, 6, 7, 7, 8, 9, 10, 11, 8, 9, 10, 11, 12, 13, 11, 12, 13, 14, 15, 16, 17, 12, 13, 14, 15, 16, 17, 18, 19, 15, 16, 17, 18, 19, 20, 21, 22, 23, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 26, 27, 28, 29, 30, 31, 32, 33
Offset: 1

Views

Author

Omar E. Pol, Jul 10 2009

Keywords

Comments

Note that the last term of the n-th row is the n-th prime A000040(n).
See also A162618 and A162619.

Examples

			Triangle begins:
.2;
.2, 3;
.3, 4, 5;
.4, 5, 6, 7;
.7, 8, 9,10,11;
.8, 9,10,11,12,13;
11,12,13,14,15,16,17;
12,13,14,15,16,17,18,19;
15,16,17,18,19,20,21,22,23;
20,21,22,23,24,25,26,27,28,29;
21,22,23,24,25,26,27,28,29,30,31;
		

Crossrefs

Showing 1-10 of 12 results. Next