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

A195825 Square array T(n,k) read by antidiagonals, n>=0, k>=1, which arises from a generalization of Euler's Pentagonal Number Theorem.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 5, 2, 1, 1, 1, 7, 3, 1, 1, 1, 1, 11, 4, 2, 1, 1, 1, 1, 15, 5, 3, 1, 1, 1, 1, 1, 22, 7, 4, 2, 1, 1, 1, 1, 1, 30, 10, 4, 3, 1, 1, 1, 1, 1, 1, 42, 13, 5, 4, 2, 1, 1, 1, 1, 1, 1, 56, 16, 7, 4, 3, 1, 1, 1, 1, 1, 1, 1, 77, 21, 10, 4
Offset: 0

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

In the infinite square array the column k is related to the generalized m-gonal numbers, where m = k+4. For example: the first column is related to the generalized pentagonal numbers A001318. The second column is related to the generalized hexagonal numbers A000217 (note that A000217 is also the entry for the triangular numbers). And so on ... (see the program in which A195152 is a table of generalized m-gonal numbers).
In the following table Euler's Pentagonal Number Theorem is represented by the entries A001318, A195310, A175003 and A000041 (see below the first row of the table):
========================================================
. Column k of
. this square
. Generalized Triangle Triangle array A195825
k m m-gonal "A" "B" [row sums of
. numbers triangle "B"
. with a(0)=1]
========================================================
...
It appears that column 2 of the square array is A006950.
It appears that column 3 of the square array is A036820.
Conjecture: if k is odd then column k contains (k+1)/2 plateaus whose levels are the first (k+1)/2 terms of A210843 and whose lengths are k+1, k-1, k-3, k-5, ... 2. Otherwise, if k is even then column k contains k/2 plateaus whose levels are the first k/2 terms of A210843 and whose lengths are k+1, k-1, k-3, k-5, ... 3. The sequence A210843 gives the levels of the plateaus of column k, when k -> infinity. For the visualization of the plateaus see the graph of a column, for example see the graph of A210964. - Omar E. Pol, Jun 21 2012

Examples

			Array begins:
    1,  1,  1,  1,  1,  1,  1,  1,  1,  1, ...
    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, ...
    5,  3,  2,  1,  1,  1,  1,  1,  1,  1, ...
    7,  4,  3,  2,  1,  1,  1,  1,  1,  1, ...
   11,  5,  4,  3,  2,  1,  1,  1,  1,  1, ...
   15,  7,  4,  4,  3,  2,  1,  1,  1,  1, ...
   22, 10,  5,  4,  4,  3,  2,  1,  1,  1, ...
   30, 13,  7,  4,  4,  4,  3,  2,  1,  1, ...
   42, 16, 10,  5,  4,  4,  4,  3,  2,  1, ...
   56, 21, 12,  7,  4,  4,  4,  4,  3,  2, ...
   77, 28, 14, 10,  5,  4,  4,  4,  4,  3, ...
  101, 35, 16, 12,  7,  4,  4,  4,  4,  4, ...
  135, 43, 21, 13, 10,  5,  4,  4,  4,  4, ...
  176, 55, 27, 14, 12,  7,  4,  4,  4,  4, ...
  ...
Column 1 is A000041 which starts: [1, 1], 2, 3, 5, 7, 11, ... The column contains only one plateau: [1, 1] which has level 1 and length 2.
Column 3 is A036820 which starts: [1, 1, 1, 1], 2, 3, [4, 4], 5, 7, 10, ... The column contains two plateaus: [1, 1, 1, 1], [4, 4], which have levels 1, 4 and lengths 4, 2.
Column 6 is A195850 which starts: [1, 1, 1, 1, 1, 1, 1], 2, 3, [4, 4, 4, 4, 4], 5, 7, 10, 12, [13, 13, 13], 14, 16, 21, ... The column contains three plateaus: [1, 1, 1, 1, 1, 1, 1], [4, 4, 4, 4, 4], [13, 13, 13], which have levels 1, 4, 13 and lengths 7, 5, 3.
		

Crossrefs

For another version see A211970.

Formula

Column k is asymptotic to exp(Pi*sqrt(2*n/(k+2))) / (8*sin(Pi/(k+2))*n). - Vaclav Kotesovec, Aug 14 2017

A036820 Number of partitions satisfying (cn(2,5) = cn(3,5) = 0).

Original entry on oeis.org

1, 1, 1, 1, 2, 3, 4, 4, 5, 7, 10, 12, 14, 16, 21, 27, 33, 37, 44, 54, 68, 80, 92, 106, 129, 155, 182, 207, 240, 283, 337, 389, 444, 508, 594, 692, 797, 902, 1030, 1187, 1373, 1564, 1770, 2004, 2295, 2624, 2978, 3349, 3783, 4293, 4880, 5501, 6174, 6932, 7830, 8834
Offset: 0

Views

Author

Keywords

Comments

For a given partition cn(i,n) means the number of its parts equal to i modulo n.
Short: (2=3 := 0).
It appears that this sequence is related to the generalized heptagonal numbers A085787 in the same way as the partition numbers A000041 are related to the generalized pentagonal numbers A001318. (See the table in comments section of A195825.) Conjecture: Column 1 of triangle A195837. Also 1 together with the row sums of triangle A195837. Also column 3 of the square array A195825. - Omar E. Pol, Oct 08 2011
Note that this sequence contains two plateaus: [1, 1, 1, 1] and [4, 4]. For more information see A195825 and A210843. - Omar E. Pol, Jun 23 2012

Examples

			G.f. = 1 + x + x^2 + x^3 + 2*x^4 + 3*x^5 + 4*x^6 + 4*x^7 + 5*x^8 + 7*x^9 + 10*x^10 + ...
G.f. = q^-9 + q^31 + q^71 + q^111 + 2*q^151 + 3*q^191 + 4*q^231 + 4*q^271 + 5*q^311 + ... - _Michael Somos_, Sep 08 2012
		

Crossrefs

Cf. A113429.

Programs

  • Maple
    with(numtheory):
    a:= proc(n) option remember; `if`(n=0, 1, add(add(d*[1, 1, 0, 0, 1]
          [1+irem(d, 5)], d=divisors(j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..60);  # Alois P. Heinz, Apr 04 2014
  • Mathematica
    a[n_] := a[n] = If[n == 0, 1, Sum[ Sum[ d*{1, 1, 0, 0, 1}[[1 + Mod[d, 5]]], {d, Divisors[j]}] * a[n-j], {j, 1, n}]/n]; Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Apr 15 2015, after Alois P. Heinz *)
  • PARI
    {a(n) = if( n<0, 0, polcoeff( 1 / prod( k=1, (n+4)\5, (1 - x^(5*k - 4)) * (1 - x^(5*k - 1)) * (1 - x^(5*k)), 1 + x * O(x^n)), n))}; /* Michael Somos, Feb 09 2012 */
    (GW-BASIC)' A program with two A-numbers:
    10 Dim A085787(100), A057077(100), a(100): a(0)=1
    20 For n = 1 to 56: For j = 1 to n
    30 If A085787(j) <= n then a(n) = a(n) + A057077(j-1)*a(n - A085787(j))
    40 Next j: Print a(n-1);: Next n ' Omar E. Pol, Jun 10 2012

Formula

Euler transform of period 5 sequence [1, 0, 0, 1, 1, ...]. - Michael Somos, Feb 09 2012
Expansion of 1 / f(-x, -x^4) in powers of x where f(, ) is Ramanujan's general theta function. - Michael Somos, Sep 08 2012
Convolution inverse of A113429. - Michael Somos, Feb 09 2012
G.f.: 1 / (Product_{k>0} (1 - x^(5*k)) * (1 - x^(5*k - 1)) * (1 - x^(5*k - 4))). - Michael Somos, Sep 08 2012
G.f.: 1 / (Sum_{k in Z} (-1)^k * x^(k * (5*k + 3) / 2)). - Michael Somos, Sep 08 2012
a(n) ~ sqrt(1+sqrt(5)) * exp(sqrt(2*n/5)*Pi) / (2^(5/2)*5^(1/4)*n). - Vaclav Kotesovec, Oct 06 2015
a(n) = (1/n)*Sum_{k=1..n} A284361(k)*a(n-k), a(0) = 1. - Seiichi Manyama, Mar 25 2017

A195836 Triangle read by rows which arises from A195826 in the same way as A175003 arises from A195310. Column k starts at row A000217(k).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 3, 1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 5, -2, 13, 7, -3, -1, 16, 10, -4, -1, 21, 13, -5, -1, 28, 16, -7, -2, 35, 21, -10, -3, 43, 28, -13, -4, 1, 55, 35, -16, -5, 1, 70, 43, -21, -7, 1, 86, 55, -28, -10, 2, 105, 70, -35, -13, 3, 130, 86, -43, -16, 4
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. It appears that this sequence is related to the generalized hexagonal numbers (A000217), A195826 and A006950 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. It appears that row sums give A006950. See comments in A195825.

Examples

			Written as a triangle:
.  1,
.  1,
.  1,   1,
.  2,   1,
.  3,   1,
.  4,   2,  -1,
.  5,   3,  -1,
.  7,   4,  -1,
. 10,   5,  -2,
. 13,   7,  -3,   -1,
. 16,  10,  -4,   -1,
. 21,  13,  -5,   -1,
. 28,  16,  -7,   -2,
. 35,  21,  -10,  -3,
. 43,  28,  -13,  -4,   1,
. 55,  35,  -16,  -5,   1,
. 70,  43,  -21,  -7,   1,
. 86,  55,  -28, -10,   2,
		

Crossrefs

A211970 Square array read by antidiagonal: T(n,k), n >= 0, k >= 0, which arises from a generalization of Euler's Pentagonal Number Theorem.

Original entry on oeis.org

1, 1, 1, 2, 1, 1, 4, 2, 1, 1, 6, 3, 1, 1, 1, 10, 5, 2, 1, 1, 1, 16, 7, 3, 1, 1, 1, 1, 24, 11, 4, 2, 1, 1, 1, 1, 36, 15, 5, 3, 1, 1, 1, 1, 1, 54, 22, 7, 4, 2, 1, 1, 1, 1, 1, 78, 30, 10, 4, 3, 1, 1, 1, 1, 1, 1, 112, 42, 13, 5, 4, 2, 1, 1, 1, 1, 1, 1
Offset: 0

Views

Author

Omar E. Pol, Jun 10 2012

Keywords

Comments

In the infinite square array if k is positive then column k is related to the generalized m-gonal numbers, where m = k+4. For example: column 1 is related to the generalized pentagonal numbers A001318. Column 2 is related to the generalized hexagonal numbers A000217 (note that A000217 is also the entry for the triangular numbers). And so on...
In the following table Euler's Pentagonal Number Theorem is represented by the entries A001318, A195310, A175003 and A000041. It seems unusual that the partition numbers are located in a middle column (see below row 1 of the table):
========================================================
. Column k of
. this square
. Generalized Triangle Triangle array A211970
k m m-gonal "A" "B" [row sums of
. numbers triangle "B"
. (if k>=1) with a(0)=1,
. if k >= 0]
========================================================
...
It appears that column 2 of the square array is A006950.
It appears that column 3 of the square array is A036820.
The partial sums of column 0 give A015128. - Omar E. Pol, Feb 09 2014

Examples

			Array begins:
1,     1,   1,   1,   1,   1,  1,  1,  1,  1,  1, ...
1,     1,   1,   1,   1,   1,  1,  1,  1,  1,  1, ...
2,     2,   1,   1,   1,   1,  1,  1,  1,  1,  1, ...
4,     3,   2,   1,   1,   1,  1,  1,  1,  1,  1, ...
6,     5,   3,   2,   1,   1,  1,  1,  1,  1,  1, ...
10,    7,   4,   3,   2,   1,  1,  1,  1,  1,  1, ...
16,   11,   5,   4,   3,   2,  1,  1,  1,  1,  1, ...
24,   15,   7,   4,   4,   3,  2,  1,  1,  1,  1, ...
36,   22,  10,   5,   4,   4,  3,  2,  1,  1,  1, ...
54,   30,  13,   7,   4,   4,  4,  3,  2,  1,  1, ...
78,   42,  16,  10,   5,   4,  4,  4,  3,  2,  1, ...
112,  56,  21,  12,   7,   4,  4,  4,  4,  3,  2, ...
160,  77,  28,  14,  10,   5,  4,  4,  4,  4,  3, ...
224, 101,  35,  16,  12,   7,  4,  4,  4,  4,  4, ...
312, 135,  43,  21,  13,  10,  5,  4,  4,  4,  4, ...
432, 176,  55,  27,  14,  12,  7,  4,  4,  4,  4, ...
...
		

Crossrefs

For another version see A195825.

Formula

T(n,k) = A211971(n), if k = 0.
T(n,k) = A195825(n,k), if k >= 1.

A195838 Triangle read by rows which arises from A195828, in the same way as A175003 arises from A195310. Column k starts at row A001082(k+1).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 4, 1, -1, 4, 1, -1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 4, -2, 12, 4, -3, 13, 5, -4, 14, 7, -4, -1, 16, 10, -4, -1, 21, 12, -5, -1, 27, 13, -7, -1, 32, 14, -10, -1, 35, 16, -12, -2, 1, 38, 21, -13, -3, 1, 44, 32, -14, -4, 1
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. This sequence is related to the generalized octagonal numbers A001082, A195828 and A195848 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. See comments in A195825.

Examples

			Written as a triangle:
.  1;
.  1;
.  1;
.  1;
.  1,   1;
.  2,   1;
.  3,   1;
.  4,   1,  -1;
.  4,   1,  -1;
.  4,   2,  -1;
.  5,   3,  -1;
.  7,   4,  -1;
. 10,   4,  -2;
. 12,   4,  -3;
. 13,   5,  -4;
. 14,   7,  -4,  -1;
. 16,  10,  -4,  -1;
. 21,  12,  -5,  -1;
. 27,  13,  -7,  -1;
. 32,  14, -10,  -1;
. 35,  16, -12,  -2,   1;
. 38,  21, -13,  -3,   1;
		

Crossrefs

Row sums give A195848.

A195827 Triangle read by rows with T(n,k) = n - A085787(k), n>=1, k>=1, if (n - A085787(k))>=0.

Original entry on oeis.org

0, 1, 2, 3, 0, 4, 1, 5, 2, 6, 3, 0, 7, 4, 1, 8, 5, 2, 9, 6, 3, 10, 7, 4, 11, 8, 5, 12, 9, 6, 0, 13, 10, 7, 1, 14, 11, 8, 2, 15, 12, 9, 3, 16, 13, 10, 4, 17, 14, 11, 5, 0, 18, 15, 12, 6, 1, 19, 16, 13, 7, 2, 20, 17, 14, 8, 3, 21, 18, 15, 9, 4, 22, 19, 16, 10, 5
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

Also triangle read by rows in which column k lists the nonnegative integers A001477 starting at the row A085787(k).
This sequence is related to the generalized heptagonal numbers A085787, A195837 and A036820 in the same way as A195310 is related to the generalized pentagonal numbers A001318, A175003 and A000041. See comments in A195825.

Examples

			Written as a triangle:
.  0;
.  1;
.  2;
.  3,  0;
.  4,  1;
.  5,  2;
.  6,  3,  0;
.  7,  4,  1;
.  8,  5,  2;
.  9,  6,  3;
. 10,  7,  4;
. 11,  8,  5;
. 12,  9,  6,  0;
. 13, 10,  7,  1;
. 14, 11,  8,  2;
		

Crossrefs

A195839 Triangle read by rows which arises from A195829, in the same way as A175003 arises from A195310. Column k starts at row A118277(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 4, -2, 12, 4, -3, 13, 4, -4, 13, 5, -4, 14, 7, -4, -1, 16, 10, -4, -1, 21, 12, -5, -1, 27, 13, -7, -1, 32, 13, -10, -1, 34, 14, -12, -1, 36, 16, -13, -2, 1
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. This sequence is related to the generalized enneagonal numbers A118277, A195829 and A195849 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. See comments in A195825.

Examples

			Written as a triangle:
.  1;
.  1;
.  1;
.  1;
.  1;
.  1,  1;
.  2,  1;
.  3,  1;
.  4,  1, -1;
.  4,  1, -1;
.  4,  1, -1;
.  4,  2, -1;
.  5,  3, -1;
.  7,  4, -1;
. 10,  4, -2;
. 12,  4, -3;
. 13,  4, -4;
. 13,  5, -4;
. 14,  7, -4, -1;
. 16, 10, -4, -1;
. 21, 12, -5, -1;
		

Crossrefs

A195840 Triangle read by rows which arises from A195830, in the same way as A175003 arises from A195310. Column k starts at row A074377(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 4, -2, 12, 4, -3, 13, 4, -4, 13, 4, -4, 13, 5, -4, 14, 7, -4, -1, 16, 10, -4, -1, 21, 12, -5, -1, 27, 13, -7, -1, 32, 13, -10, -1, 34
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. This sequence is related to the generalized decagonal numbers A074377, A195830 and A195850 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. See comments in A195825.

Examples

			Written as a triangle:
.  1;
.  1;
.  1;
.  1;
.  1;
.  1;
.  1,  1;
.  2,  1;
.  3,  1;
.  4,  1,  -1;
.  4,  1,  -1;
.  4,  1,  -1;
.  4,  1,  -1;
.  4,  2,  -1;
.  5,  3,  -1;
.  7,  4,  -1;
. 10,  4,  -2;
. 12,  4,  -3;
. 13,  4,  -4;
. 13,  4,  -4;
. 13,  5,  -4;
. 14,  7,  -4,  -1;
. 16, 10,  -4,  -1;
. 21, 12,  -5,  -1;
. 27, 13,  -7,  -1;
. 32, 13, -10,  -1;
. 34, 13, -12,  -1,  1;
		

Crossrefs

A195841 Triangle read by rows which arises from A195831, in the same way as A175003 arises from A195310. Column k starts at row A195160(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 4, -2, 12, 4, -3, 13, 4, -4, 13, 4, -4, 13, 4, -4, 13, 5, -4, 14, 7, -4, -1, 16, 10, -4, -1, 21, 12, -5, -1, 27, 13, -7, -1
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. This sequence is related to the generalized hendecagonal numbers A195160, A195831 and A195851 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. See comments in A195825.

Examples

			Written as a triangle:
1;
1;
1;
1;
1;
1;
1;
1, 1;
2, 1;
3, 1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 2, -1;
5, 3, -1;
7, 4, -1;
		

Crossrefs

A195842 Triangle read by rows which arises from A195832, in the same way as A175003 arises from A195310. Column k starts at row A195162(k).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 1, -1, 4, 2, -1, 5, 3, -1, 7, 4, -1, 10, 4, -2, 12, 4, -3, 13, 4, -4, 13, 4, -4, 13, 4, -4, 13, 4, -4, 13, 5, -4, 14, 7, -4, -1, 16, 10, -4, -1, 21, 12, -5, -1
Offset: 1

Views

Author

Omar E. Pol, Sep 24 2011

Keywords

Comments

The sum of terms of row n is equal to the leftmost term of row n+1. This sequence is related to the generalized dodecagonal numbers A195162, A195832 and A195852 in the same way as A175003 is related to the generalized pentagonal numbers A001318, A195310 and A000041. See comments in A195825.

Examples

			Written as a triangle:
1;
1;
1;
1;
1;
1;
1;
1;
1, 1;
2, 1;
3, 1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 1, -1;
4, 2, -1;
5, 3, -1;
7, 4, -1;
		

Crossrefs

Showing 1-10 of 12 results. Next