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.

Previous Showing 11-18 of 18 results.

A195852 Column 8 of array A195825. Also column 1 of triangle A195842. Also 1 together with the row sums of triangle A195842.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 4, 4, 4, 4, 4, 4, 5, 7, 10, 12, 13, 13, 13, 13, 13, 14, 16, 21, 27, 32, 34, 35, 35, 35, 36, 38, 44, 54, 67, 77, 83, 85, 86, 87, 89, 95, 107, 128, 152, 173, 185, 191, 194, 197, 203, 216, 242, 281, 328, 367, 393, 407
Offset: 0

Views

Author

Omar E. Pol, Oct 07 2011

Keywords

Comments

Note that this sequence contains four plateaus: [1, 1, 1, 1, 1, 1, 1, 1, 1], [4, 4, 4, 4, 4, 4, 4], [13, 13, 13, 13, 13], [35, 35, 35]. For more information see A210843 and other sequences of this family. - Omar E. Pol, Jun 29 2012
Number of partitions of n into parts congruent to 0, 1 or 9 (mod 10). - Peter Bala, Dec 10 2020

Crossrefs

Formula

G.f.: Product_{k>=1} 1/((1 - x^(10*k))*(1 - x^(10*k-1))*(1 - x^(10*k-9))). - Ilya Gutkovskiy, Aug 13 2017
a(n) ~ exp(Pi*sqrt(n/5))/(2*(sqrt(5)-1)*n). - Vaclav Kotesovec, Aug 14 2017
a(n) = a(n-1) + a(n-9) - a(n-12) - a(n-28) + + - - (with the convention a(n) = 0 for negative n), where 1, 9, 12, 28, ... is the sequence of generalized 12-gonal numbers A195162. - Peter Bala, Dec 10 2020

Extensions

More terms from Omar E. Pol, Jun 10 2012

A303070 a(n) = [x^n] (1/(1 - x))*Product_{k>=1} 1/(1 - x^k)^n.

Original entry on oeis.org

1, 2, 8, 35, 164, 787, 3857, 19147, 96004, 485009, 2465013, 12589315, 64555985, 332158127, 1714001409, 8866730665, 45968787524, 238778897128, 1242417984179, 6474394344503, 33784931507529, 176515163156311, 923265560495737, 4834081924982522, 25334170138318345, 132883719945537587
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 18 2018

Keywords

Crossrefs

Main diagonal of A210764.

Programs

  • Mathematica
    Table[SeriesCoefficient[1/(1 - x) Product[1/(1 - x^k)^n, {k, 1, n}], {x, 0, n}], {n, 0, 25}]
    Table[SeriesCoefficient[1/(1 - x) Exp[n Sum[x^k/(k (1 - x^k)), {k, 1, n}]], {x, 0, n}], {n, 0, 25}]

Formula

a(n) = [x^n] (1/(1 - x))*exp(n*Sum_{k>=1} x^k/(k*(1 - x^k))).
a(n) = A210764(n,n) = Sum_{j=0..n} A144064(j,n).
a(n) ~ c * d^n / sqrt(n), where d = A270915 = 5.352701333486642687772415814165... and c = 0.4068869940800214657298372785820... - Vaclav Kotesovec, May 19 2018

A210764 Square array T(n,k), n>=0, k>=0, read by antidiagonals in which column k gives the partial sums of column k of A144064.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 3, 1, 1, 7, 8, 4, 1, 1, 12, 18, 13, 5, 1, 1, 19, 38, 35, 19, 6, 1, 1, 30, 74, 86, 59, 26, 7, 1, 1, 45, 139, 194, 164, 91, 34, 8, 1, 1, 67, 249, 415, 416, 281, 132, 43, 9, 1, 1, 97, 434, 844, 990, 787, 447, 183, 53, 10, 1
Offset: 0

Views

Author

Omar E. Pol, Jun 27 2012

Keywords

Comments

It appears that row 2 is A034856.
Observation:
Column 1 is the EULER transform of 2,1,1,1,1,1,1,1...
Column 2 is the EULER transform of 3,2,2,2,2,2,2,2...

Examples

			Array begins:
1,   1,   1,   1,   1,   1,   1,   1,   1,   1,   1,
1,   2,   3,   4,   5,   6,   7,   8,   9,  10,
1,   4,   8,  13,  19,  26,  34,  43,  53,
1,   7,  18,  35,  59,  91, 132, 183,
1,  12,  38,  86, 164, 281, 447,
1,  19,  74, 194, 416, 787,
1,  30, 139, 415, 990,
1,  45, 249, 844,
1,  67, 434,
1,  97,
1,
		

Crossrefs

Columns (0-3): A000012, A000070, A000713, A210843.
Rows (0-1): A000012, A000027.
Main diagonal gives A303070.

Programs

  • Maple
    with(numtheory):
    etr:= proc(p) local b;
            b:= proc(n) option remember; `if`(n=0, 1,
                  add(add(d*p(d), d=divisors(j))*b(n-j), j=1..n)/n)
                end
          end:
    A:= (n, k)-> etr(j-> k +`if`(j=1, 1, 0))(n):
    seq(seq(A(d-k, k), k=0..d), d=0..14); # Alois P. Heinz, May 20 2013
  • Mathematica
    etr[p_] := Module[{b}, b[n_] := b[n] = If[n == 0, 1, Sum[Sum[d*p[d], {d, Divisors[ j]}]*b[n-j], {j, 1, n}]/n]; b]; A[n_, k_] := etr[Function[{j}, k + If[j == 1, 1, 0]]][n]; Table[Table[A[d-k, k], {k, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Mar 05 2015, after Alois P. Heinz *)

A353690 Irregular triangle read by rows: T(n,k), n>=1, k>=1, in which column k lists the numbers of A353689 multiplied by A000330(k), and the first element of column k is in row A000217(k).

Original entry on oeis.org

1, 5, 18, 5, 53, 25, 139, 90, 333, 265, 14, 748, 695, 70, 1592, 1665, 252, 3246, 3740, 742, 6379, 7960, 1946, 30, 12152, 16230, 4662, 150, 22524, 31895, 10472, 540, 40764, 60760, 22288, 1590, 72213, 112620, 45444, 4170, 125505, 203820, 89306, 9990, 55, 214378, 361065, 170128, 22440, 275
Offset: 1

Views

Author

Omar E. Pol, May 04 2022

Keywords

Comments

The alternating sum of the n-th row equals A175254(n), the volume of the stepped pyramid with n levels described in A245092, also the n-th term of the convolution of A000203 and A000027.
Column k is the partial sums of the k-th column of the triangle A249120.
Another triangle with the same row lengths and whose alternating row sums give A175254 is A262612.

Examples

			Triangle begins:
        1;
        5;
       18,       5;
       53,      25;
      139,      90;
      333,     265,      14;
      748,     695,      70;
     1592,    1665,     252;
     3246,    3740,     742;
     6379,    7960,    1946,     30;
    12152,   16230,    4662,    150;
    22524,   31895,   10472,    540;
    40764,   60760,   22288,   1590;
    72213,  112620,   45444,   4170;
   125505,  203820,   89306,   9990,    55;
   214378,  361065,  170128,  22440,   275;
   360473,  627525,  315336,  47760,   990;
   597450, 1071890,  570696,  97380,  2915;
   977196, 1802365, 1010982, 191370,  7645;
  1578852, 2987250, 1757070, 364560, 18315;
  2522157, 4885980, 3001292, 675720, 41140, 91;
  ...
For n = 6 we have that A175254(6) is equal to [1] + [1 + 3] + [1 + 3 + 4] + [1 + 3 + 4 + 7] + [1 + 3 + 4 + 7 + 6] + [1 + 3 + 4 + 7 + 6 + 12] = 1 + 4 + 8 + 15 + 21 + 33 = 82. On the other hand the alternating sum of the 6th row of the triangle is 333 - 265 + 14 = 82, equaling A175254(6).
		

Crossrefs

Column 1 is A353689.
Row n has length A003056(n).
Column k starts in row A000217(k).
The first element in column k is A000330(k).
Alternating row sums give A175254.

Formula

A175254(n) = Sum_{k=1..A003056(n)} (-1)^(k-1)*T(n,k).

A384999 Irregular triangle read by rows: T(n,k) is the total number of partitions of all numbers <= n with k designated summands, n >= 0, 0 <= k <= A003056(n).

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 8, 1, 1, 15, 4, 1, 21, 13, 1, 33, 28, 1, 1, 41, 58, 4, 1, 56, 103, 13, 1, 69, 170, 35, 1, 87, 269, 77, 1, 1, 99, 404, 158, 4, 1, 127, 579, 298, 13, 1, 141, 810, 529, 35, 1, 165, 1116, 880, 86, 1, 189, 1470, 1431, 183, 1, 1, 220, 1935, 2214, 371, 4, 1, 238, 2475, 3348, 701, 13
Offset: 0

Views

Author

Omar E. Pol, Jul 22 2025

Keywords

Comments

When part i has multiplicity j > 0 exactly one part i is "designated".
The length of the row n is A002024(n+1) = 1 + A003056(n), hence the first positive element in column k is in the row A000217(k).
Column k gives the partial sums of the column k of A385001.
Columns converge to A210843 which is also the partial sums of A000716.

Examples

			Triangle begins:
---------------------------------------------
   n\k:   0    1     2      3     4    5   6
---------------------------------------------
   0 |    1;
   1 |    1,   1;
   2 |    1,   4;
   3 |    1,   8,    1;
   4 |    1,  15,    4;
   5 |    1,  21,   13;
   6 |    1,  33,   28,     1;
   7 |    1,  41,   58,     4;
   8 |    1,  56,  103,    13;
   9 |    1,  69,  170,    35;
  10 |    1,  87,  269,    77,    1;
  11 |    1,  99,  404,   158,    4;
  12 |    1, 127,  579,   298,   13;
  13 |    1, 141,  810,   529,   35;
  14 |    1, 165, 1116,   880,   86;
  15 |    1, 189, 1470,  1431,  183,   1;
  16 |    1, 220, 1935,  2214,  371,   4;
  17 |    1, 238, 2475,  3348,  701,  13;
  18 |    1, 277, 3156,  4894, 1269,  35;
  19 |    1, 297, 3921,  7036, 2187,  86;
  20 |    1, 339, 4866,  9871, 3639, 194;
  21 |    1, 371, 5906, 13629, 5872, 402,  1;
  ...
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+add(expand(b(n-i*j, i-1)*j*x), j=1..n/i)))
        end:
    g:= proc(n) option remember; `if`(n<0, 0, g(n-1)+b(n$2)) end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..degree(p)))(g(n)):
    seq(T(n), n=0..20);  # Alois P. Heinz, Jul 22 2025

A233969 Partial sums of A006950.

Original entry on oeis.org

1, 2, 3, 5, 8, 12, 17, 24, 34, 47, 63, 84, 112, 147, 190, 245, 315, 401, 506, 636, 797, 993, 1229, 1516, 1866, 2286, 2787, 3389, 4111, 4969, 5985, 7191, 8622, 10309, 12290, 14621, 17362, 20568, 24308, 28676, 33772, 39694, 46562, 54529, 63762, 74432, 86738
Offset: 0

Views

Author

Omar E. Pol, Jan 12 2014

Keywords

Comments

The first three columns of A211970 are A211971, A000041, A006950, so for k = 0..2, the partial sums of column k of A211970 give: A015128, A000070, this sequence.

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+`if`(i>n, 0, b(n-i, i-irem(i, 2)))))
        end:
    a:= proc(n) option remember; b(n, n) +`if`(n>0, a(n-1), 0) end:
    seq(a(n), n=0..50);  # Alois P. Heinz, Jan 12 2014
  • Mathematica
    Accumulate[CoefficientList[Series[x*QPochhammer[-1/x, x^2]/((1 + x) * QPochhammer[x^2]), {x, 0, 50}], x]] (* Vaclav Kotesovec, Oct 27 2016 *)

Formula

a(n) ~ exp(Pi*sqrt(n/2))/(2*Pi*sqrt(n)). - Vaclav Kotesovec, Oct 27 2016

A210992 Square array read by antidiagonals, in which column k starts with k plateaus of lengths k+1, k, k-1, k-2, k-3,..2 and of levels A000124: 1, 2, 4, 7, 11..., if k >= 1, connected by consecutive integers. After the last plateau the length remains 1.

Original entry on oeis.org

1, 2, 1, 3, 1, 1, 4, 2, 1, 1, 5, 3, 1, 1, 1, 6, 4, 2, 1, 1, 1, 7, 5, 2, 1, 1, 1, 1, 8, 6, 3, 2, 1, 1, 1, 1, 9, 7, 4, 2, 1, 1, 1, 1, 1, 10, 8, 5, 2, 2, 1, 1, 1, 1, 1, 11, 9, 6, 3, 2, 1, 1, 1, 1, 1, 1, 12, 10, 7, 4, 2, 2, 1, 1, 1, 1, 1, 1, 13, 11, 8, 4, 2, 2
Offset: 0

Views

Author

Omar E. Pol, Jun 30 2012

Keywords

Comments

Column k contains k plateaus whose levels are the first k terms of A000124, therefore A000124(i) is the level of the i-th plateau of the column k when k -> infinity.
Column k contains the integers s>=1 repeated f(s) times, sorted, where f(s)=1 if s is not in A000124, otherwise, if A000124(c)=s, repeated f(s)=max(1,k+1-c) times. - R. J. Mathar, Jul 22 2012
It appears that this array can be represented by a structure in which the number of relevant nodes give A000005 (see also A210959). - Omar E. Pol, Jul 24 2012

Examples

			Illustration of initial terms of the 4th column:
------------------------------------------------------
Level    Graphic
------------------------------------------------------
10                                              *
9                                             *
8                                           *
7                                       * *
6                                     *
5                                   *
4                             * * *
3                           *
2                   * * * *
1         * * * * *
0
-------------------------------------------------------
Column 4: 1,1,1,1,1,2,2,2,2,3,4,4,4,5,6,7,7,8,9,10,...
-------------------------------------------------------
Array begins:
1, 1, 1, 1, 1, 1, 1, 1, 1, 1,...
2, 1, 1, 1, 1, 1, 1, 1, 1, 1,...
3, 2, 1, 1, 1, 1, 1, 1, 1, 1,...
4, 3, 2, 1, 1, 1, 1, 1, 1, 1,...
5, 4, 2, 2, 1, 1, 1, 1, 1, 1,...
6, 5, 3, 2, 2, 1, 1, 1, 1, 1,...
7, 6, 4, 2, 2, 2, 1, 1, 1, 1,...
8, 7, 5, 3, 2, 2, 2, 1, 1, 1,...
9, 8, 6, 4, 2, 2, 2, 2, 1, 1,...
		

Crossrefs

Programs

  • Maple
    A000124i := proc(n)
        local j;
        for j from 0 do
            if A000124(j) = n then
                return j;
            elif A000124(j) > n then
                return -1 ;
            end if;
        end do:
    end proc:
    A210992 := proc(n,k)
        local f,r,a,c;
        f := k+1  ;
        a := 1 ;
        for r from 0 to n do
            if f > 0 then
                f := f-1;
            else
                a := a+1 ;
                c := A000124i(a) ;
                f := 0 ;
                if c >= 0 then
                    f := max(0,k-c) ;
                end if;
            end if;
        end do:
        a ;
    end proc: # R. J. Mathar, Jul 22 2012

A353689 Convolution of A000716 and the positive integers.

Original entry on oeis.org

1, 5, 18, 53, 139, 333, 748, 1592, 3246, 6379, 12152, 22524, 40764, 72213, 125505, 214378, 360473, 597450, 977196, 1578852, 2522157, 3986658, 6239619, 9675801, 14874445, 22679693, 34314378, 51539173, 76875314, 113913453, 167741728, 245534597, 357361857, 517293186
Offset: 0

Views

Author

Omar E. Pol, May 08 2022

Keywords

Crossrefs

Partial sums of A210843.
Column 1 of A353690.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(
          a(n-j)*(2+3*numtheory[sigma](j)), j=1..n)/n)
        end:
    seq(a(n), n=0..35);  # Alois P. Heinz, May 11 2022
  • Mathematica
    nmax = 35; CoefficientList[Series[1/(1 - x)^2 * Product[1/(1 - x^k)^3, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, May 11 2022 *)
  • PARI
    lista(nn) = Vec(1/(eta('x+O('x^nn))^3*(1-x)^2)); \\ Michel Marcus, May 09 2022

Formula

From Vaclav Kotesovec, May 11 2022: (Start)
G.f.: 1/(1-x)^2 * Product_{k>=1} 1/(1-x^k)^3.
a(n) ~ exp(Pi*sqrt(2*n)) / (2^(5/2) * Pi^2 * sqrt(n)). (End)
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