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 1-9 of 9 results.

A053253 Coefficients of the '3rd-order' mock theta function omega(q).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 10, 14, 18, 22, 29, 36, 44, 56, 68, 82, 101, 122, 146, 176, 210, 248, 296, 350, 410, 484, 566, 660, 772, 896, 1038, 1204, 1391, 1602, 1846, 2120, 2428, 2784, 3182, 3628, 4138, 4708, 5347, 6072, 6880, 7784, 8804, 9940, 11208, 12630
Offset: 0

Views

Author

Dean Hickerson, Dec 19 1999

Keywords

Comments

Empirical: a(n) is the number of integer partitions mu of 2n+1 such that the diagram of mu has an odd number of cells in each row and in each column. - John M. Campbell, Apr 24 2020
From Gus Wiseman, Jun 26 2022: (Start)
By Campbell's conjecture above that a(n) is the number of partitions of 2n+1 with all odd parts and all odd conjugate parts, the a(0) = 1 through a(5) = 8 partitions are (B = 11):
(1) (3) (5) (7) (9) (B)
(111) (311) (511) (333) (533)
(11111) (31111) (711) (911)
(1111111) (51111) (33311)
(3111111) (71111)
(111111111) (5111111)
(311111111)
(11111111111)
These partitions are ranked by A352143. (End)

References

  • Srinivasa Ramanujan, The Lost Notebook and Other Unpublished Papers, Narosa Publishing House, New Delhi, 1988, pp. 15, 17, 31.

Crossrefs

Other '3rd-order' mock theta functions are at A000025, A053250, A053251, A053252, A053254, A053255, A261401.
Cf. A095913(n)=a(n-3).
Cf. A259094.
Conjectured to count the partitions ranked by A352143.
A069911 = strict partitions w/ all odd parts, ranked by A258116.
A078408 = partitions w/ all odd parts, ranked by A066208.
A117958 = partitions w/ all odd parts and multiplicities, ranked by A352142.

Programs

  • Mathematica
    Series[Sum[q^(2n(n+1))/Product[1-q^(2k+1), {k, 0, n}]^2, {n, 0, 6}], {q, 0, 100}]
  • PARI
    {a(n)=local(A); if(n<0, 0, A=1+x*O(x^n); polcoeff( sum(k=0, (sqrtint(2*n+1)-1)\2, A*=(x^(4*k)/(1-x^(2*k+1))^2 +x*O(x^(n-2*(k^2-k))))), n))} /* Michael Somos, Aug 18 2006 */
    
  • PARI
    {a(n)=local(A); if(n<0, 0, n++; A=1+x*O(x^n); polcoeff( sum(k=0, n-1, A*=(x/(1-x^(2*k+1)) +x*O(x^(n-k)))), n))} /* Michael Somos, Aug 18 2006 */

Formula

G.f.: omega(q) = Sum_{n>=0} q^(2*n*(n+1))/((1-q)*(1-q^3)*...*(1-q^(2*n+1)))^2.
G.f.: Sum_{k>=0} x^k/((1-x)(1-x^3)...(1-x^(2k+1))). - Michael Somos, Aug 18 2006
G.f.: (1 - G(0))/(1-x) where G(k) = 1 - 1/(1-x^(2*k+1))/(1-x/(x-1/G(k+1) )); (continued fraction). - Sergei N. Gladkovskii, Jan 18 2013
a(n) ~ exp(Pi*sqrt(n/3)) / (4*sqrt(n)). - Vaclav Kotesovec, Jun 10 2019
Conjectural g.f.: 1/(1 - x)*( 1 + Sum_{n >= 0} x^(3*n+1) /((1 - x)*(1 - x^3)*...*(1 - x^(2*n+1))) ). - Peter Bala, Nov 18 2024

A008672 Expansion of 1/((1-x)*(1-x^3)*(1-x^5)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 17, 18, 20, 22, 23, 25, 27, 29, 31, 33, 35, 37, 40, 42, 44, 47, 49, 52, 55, 57, 60, 63, 66, 69, 72, 75, 78, 82, 85, 88, 92, 95, 99, 103, 106, 110, 114, 118, 122, 126, 130, 134, 139, 143, 147, 152, 156, 161, 166
Offset: 0

Views

Author

Keywords

Comments

Number of partitions of n into odd parts less than or equal to 5.
1/((1-x^2)*(1-x^6)*(1-x^10)) is the Molien series for the icosahedral group [3,5] of order 120.
Number of partitions (d1,d2,d3) of n such that 0 <= d1/1 <= d2/2 <= d3/3. - Seiichi Manyama, Jun 04 2017

Examples

			G.f. = 1 + x + x^2 + 2*x^3 + 2*x^4 + 3*x^5 + 4*x^6 + 4*x^7 + 5*x^8 + 6*x^9 + 7*x^10 + ...
		

References

  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 120, D(n;1,3,5).
  • W. Ebeling, Lattices and Codes, Vieweg; 2nd ed., 2002, see p. 164 etc.
  • F. Hirzebruch, Letter to N. J. A. Sloane, quoted in Ges. Abh. II, 796-798.
  • F. Klein, Lectures on the Icosahedron ..., 2nd Rev. Ed., 1913; reprinted by Dover, NY, 1956; see pp. 236-243.
  • L. Smith, Polynomial Invariants of Finite Groups, Peters, 1995, p. 199 (No. 23).

Crossrefs

Programs

  • GAP
    List([0..70], n-> Int((n^2+9*n+30)/30) ); # G. C. Greubel, Sep 08 2019
  • Magma
    [Round((n+3)*(n+6)/30): n in [0..60]]; // Vincenzo Librandi, Jun 23 2011
    
  • Maple
    seq(coeff(series(1/((1-x)*(1-x^3)*(1-x^5)), x, n+1), x, n), n = 0..70); # G. C. Greubel, Sep 08 2019
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-x^3)(1-x^5)),{x,0,70}],x] (* or *) LinearRecurrence[{1,0,1,-1,1,-1,0,-1,1},{1,1,1,2,2,3,4,4,5},70] (* Harvey P. Dale, Feb 07 2012 *)
  • PARI
    {a(n) = (n^2 + 9*n)\30 + 1} /* Michael Somos, Nov 25 2002 */
    
  • Sage
    [floor((n^2+9*n+30)/30) for n in (0..70)] # G. C. Greubel, Sep 08 2019
    

Formula

a(n) = round((n+3)*(n+6)/30).
a(n) = A025799(2n).
a(n) = floor(n^2/30 + 3*n/10 + 1). - Michael Somos, Nov 25 2002
G.f.: 1/((1-x)*(1-x^3)*(1-x^5)).
a(n) = a(-9 - n). - Michael Somos, Nov 16 2005
a(n) = a(n-1) + a(n-3) - a(n-4) + a(n-5) - a(n-6) - a(n-8) + a(n-9); a(0)=1, a(1)=1, a(2)=1, a(3)=2, a(4)=2, a(5)=3, a(6)=4, a(7)=4, a(8)=5. - Harvey P. Dale, Feb 07 2012

A008673 Expansion of 1/((1-x)*(1-x^3)*(1-x^5)*(1-x^7)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 7, 9, 10, 12, 14, 16, 19, 21, 24, 27, 30, 34, 38, 42, 46, 51, 56, 61, 67, 73, 79, 86, 93, 100, 108, 116, 125, 134, 143, 153, 163, 174, 185, 197, 209, 221, 235, 248, 262, 277, 292, 308, 324, 341, 358, 376, 395, 414, 434, 454, 475, 497, 519, 542, 566, 590
Offset: 0

Views

Author

Keywords

Comments

Number of partitions of n into parts 1, 3, 5, and 7. - Joerg Arndt, Jul 08 2013
Number of partitions (d1,d2,d3,d4) of n such that 0 <= d1/1 <= d2/2 <= d3/3 <= d4/4. - Seiichi Manyama, Jun 04 2017

Examples

			There are a(7)=5 partitions of n=7 into parts 1, 3, 5, and 7: (7), (511), (331), (31111), and (1111111). - _David Neil McGrath_, Feb 14 2015
		

Crossrefs

Cf. A259094.

Programs

  • GAP
    List([0..70], n-> Int((n^3+24*n^2+171*n+630)/630) ); # G. C. Greubel, Sep 08 2019
  • Magma
    [Floor((n^3+24*n^2+171*n+630)/630): n in [0..70]]; // G. C. Greubel, Sep 08 2019
    
  • Maple
    seq(coeff(series(1/((1-x)*(1-x^3)*(1-x^5)*(1-x^7)), x, n+1), x, n), n = 0 .. 70); # G. C. Greubel, Sep 08 2019
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-x^3)(1-x^5)(1-x^7)), {x,0,70}], x] (* Vincenzo Librandi, Jun 22 2013 *)
    LinearRecurrence[{1,0,1,-1,1,-1,1,-2,1,-1,1,-1,1,0,1,-1}, {1,1,1,2,2,3, 4,5,6,7,9,10,12,14,16,19}, 70] (* Harvey P. Dale, Jul 08 2019 *)
  • PARI
    vector(70, n, m=n-1; (m^3+24*m^2+171*m+630)\630 ) \\ G. C. Greubel, Sep 08 2019
    
  • Sage
    [floor((n^3+24*n^2+171*n+630)/630) for n in (0..70)] # G. C. Greubel, Sep 08 2019
    

Formula

a(n) = floor((n^3 + 24*n^2 + 171*n + 630)/630). - Tani Akinari, Jul 08 2013
a(n) = a(n-1) + a(n-3) - a(n-4) + a(n-5) - a(n-6) + a(n-7) - 2*a(n-8) + a(n-9) - a(n-10) + a(n-11) - a(n-12) + a(n-13) + a(n-15) - a(n-16). - David Neil McGrath, Feb 14 2015

A008674 Expansion of 1/((1-x)*(1-x^3)*(1-x^5)*(1-x^7)*(1-x^9)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 11, 14, 16, 19, 23, 26, 30, 35, 40, 45, 52, 58, 65, 74, 82, 91, 102, 113, 124, 138, 151, 165, 182, 198, 216, 236, 256, 277, 301, 325, 350, 379, 407, 437, 471, 504, 539, 578, 617, 658, 703, 748, 795, 847, 899, 953, 1012, 1071, 1133, 1200, 1267, 1337, 1413, 1489, 1568, 1653
Offset: 0

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Author

Keywords

Comments

Number of partitions of n into odd parts <= 9. - Seiichi Manyama, Jun 04 2017
Number of partitions (d1,d2,...,d5) of n such that 0 <= d1/1 <= d2/2 <= ... <= d5/5. - Seiichi Manyama, Jun 04 2017

Crossrefs

Cf. A259094.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 70); Coefficients(R!( 1/&*[1-x^(2*j+1): j in [0..4]] )); // G. C. Greubel, Sep 08 2019
    
  • Maple
    seq(coeff(series(1/mul(1-x^(2*j+1), j=0..4), x, n+1), x, n), n = 0..70); # G. C. Greubel, Sep 08 2019
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-x^3)(1-x^5)(1-x^7)(1-x^9)), {x,0,70}], x] (* Vincenzo Librandi, Jun 22 2013 *)
    LinearRecurrence[{1,0,1,-1,1,-1,1,-2,2,-2,1,-2,2,-1,2,-2,2,-1,1,-1,1,-1, 0,-1,1}, {1,1,1,2,2,3,4,5,6,8,10,11,14,16,19,23,26,30,35,40,45,52,58, 65,74}, 70] (* Harvey P. Dale, Aug 13 2016 *)
  • PARI
    my(x='x+O('x^70)); Vec(1/prod(j=0,4,1-x^(2*j+1)) ) \\ G. C. Greubel, Sep 08 2019
    
  • PARI
    a(n) = (n^4+50*n^3+855*n^2+6030*n - n*280*(n%3) +23800)\22680 \\ Hoang Xuan Thanh, Aug 12 2025
  • Sage
    def A008674_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/prod(1-x^(2*j+1) for j in (0..4)) ).list()
    A008674_list(70) # G. C. Greubel, Sep 08 2019
    

Formula

a(n) = floor((n^4+50*n^3+855*n^2+6030*n+23800)/22680 - n*(n mod 3)/81). - Hoang Xuan Thanh, Aug 12 2025

Extensions

Typo in name fixed by Vincenzo Librandi, Jun 22 2013

A008675 Expansion of 1/( Product_{j=0..5} (1-x^(2*j+1)) ).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 21, 25, 29, 34, 40, 46, 53, 62, 70, 80, 91, 103, 116, 131, 147, 164, 184, 204, 227, 252, 278, 307, 339, 372, 408, 448, 489, 534, 583, 634, 689, 749, 811, 878, 950, 1025, 1106, 1192, 1282, 1378, 1481, 1588, 1702, 1823, 1949, 2083
Offset: 0

Views

Author

Keywords

Comments

Number of partitions of n into parts 1, 3, 5, 7, 9, and 11. - Joerg Arndt, Jul 09 2013
Number of partitions (d1,d2,...,d6) of n such that 0 <= d1/1 <= d2/2 <= ... <= d6/6. - Seiichi Manyama, Jun 04 2017

Crossrefs

Cf. A259094.

Programs

  • Magma
    R:=PowerSeriesRing(Integers(), 65); Coefficients(R!( 1/&*[1-x^(2*j+1): j in [0..5]] )); // G. C. Greubel, Sep 08 2019
    
  • Maple
    seq(coeff(series(1/mul(1-x^(2*j+1), j=0..5), x, n+1), x, n), n = 0..65); # G. C. Greubel, Sep 08 2019
  • Mathematica
    CoefficientList[Series[1/((1-x)(1-x^3)(1-x^5)(1-x^7)(1-x^9)(1-x^11)), {x, 0, 65}], x] (* Vincenzo Librandi, Jun 23 2013 *)
    LinearRecurrence[{1,0,1,-1,1,-1,1,-2,2,-2,2,-3,2,-2,3,-3,3,-2,3,-3,3,-2,2,-3,2,-2,2,-2,1,-1,1,-1,1,0,1,-1},{1,1,1,2,2,3,4,5,6,8,10,12,15,17,21,25,29,34,40,46,53,62,70,80,91,103,116,131,147,164,184,204,227,252,278,307},60] (* Harvey P. Dale, Oct 29 2022 *)
  • PARI
    a(n)=(46200*((n\3+1)*[2,-1,-1][n%3+1]+[10,-4,-7][n%3+1]) +3*n^5+ 270*n^4+9005*n^3+136350*n^2+908260*n+3603600)\3742200  \\ Tani Akinari, Jul 09 2013
    
  • PARI
    Vec(1/((1-x)*(1-x^3)*(1-x^5)*(1-x^7)*(1-x^9)*(1-x^11))+O(x^66)) \\ Joerg Arndt, Jul 09 2013
    
  • Sage
    def A008674_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/prod(1-x^(2*j+1) for j in (0..5)) ).list()
    A008674_list(65) # G. C. Greubel, Sep 08 2019

Extensions

Typo in name fixed by Vincenzo Librandi, Jun 23 2013

A287997 Expansion of 1/((1-x)(1-x^3)(1-x^5) ... (1-x^13)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 22, 26, 31, 36, 43, 50, 58, 68, 78, 90, 103, 118, 134, 153, 173, 195, 220, 247, 277, 310, 346, 385, 429, 475, 526, 582, 642, 707, 778, 854, 936, 1026, 1121, 1224, 1335, 1454, 1581, 1718, 1864, 2020, 2188, 2366, 2556
Offset: 0

Views

Author

Seiichi Manyama, Jun 04 2017

Keywords

Comments

Number of partitions of n into odd parts less than or equal to 13.
Number of partitions (d1,d2,...,d7) of n such that 0 <= d1/1 <= d2/2 <= ... <= d7/7.

Crossrefs

Cf. A259094.

A287998 Expansion of 1/((1-x)(1-x^3)(1-x^5) ... (1-x^15)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 22, 27, 32, 37, 45, 52, 61, 72, 83, 96, 111, 128, 146, 168, 191, 217, 247, 279, 314, 355, 398, 446, 501, 558, 622, 693, 770, 853, 946, 1045, 1153, 1273, 1400, 1538, 1690, 1852, 2027, 2219, 2422, 2642, 2881, 3136, 3409
Offset: 0

Views

Author

Seiichi Manyama, Jun 04 2017

Keywords

Comments

Number of partitions of n into odd parts less than or equal to 15.
Number of partitions (d1,d2,...,d8) of n such that 0 <= d1/1 <= d2/2 <= ... <= d8/8.

Crossrefs

Cf. A259094.

A288000 Expansion of 1/((1-x)(1-x^3)(1-x^5) ... (1-x^17)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 22, 27, 32, 38, 46, 53, 63, 74, 86, 100, 116, 134, 154, 178, 203, 232, 265, 301, 341, 387, 436, 492, 554, 621, 696, 779, 870, 969, 1080, 1199, 1331, 1476, 1632, 1803, 1991, 2193, 2414, 2655, 2914, 3196, 3502, 3832
Offset: 0

Views

Author

Seiichi Manyama, Jun 04 2017

Keywords

Comments

Number of partitions of n into odd parts less than or equal to 17.
Number of partitions (d1,d2,...,d9) of n such that 0 <= d1/1 <= d2/2 <= ... <= d9/9.

Crossrefs

Cf. A259094.

A288001 Expansion of 1/((1-x)(1-x^3)(1-x^5) ... (1-x^19)).

Original entry on oeis.org

1, 1, 1, 2, 2, 3, 4, 5, 6, 8, 10, 12, 15, 18, 22, 27, 32, 38, 46, 54, 64, 75, 88, 102, 119, 138, 159, 184, 211, 242, 277, 316, 359, 409, 463, 524, 592, 667, 750, 843, 945, 1057, 1182, 1318, 1469, 1635, 1816, 2014, 2233, 2470, 2730, 3014, 3323, 3659, 4026
Offset: 0

Views

Author

Seiichi Manyama, Jun 04 2017

Keywords

Comments

Number of partitions of n into odd parts less than or equal to 19.
Number of partitions (d1,d2,...,d10) of n such that 0 <= d1/1 <= d2/2 <= ... <= d10/10.

Crossrefs

Cf. A259094.

Programs

  • Mathematica
    CoefficientList[Series[1/Times@@Table[(1-x^exp),{exp,Range[1,19,2]}],{x,0,60}],x] (* Harvey P. Dale, Mar 08 2025 *)
Showing 1-9 of 9 results.