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.

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A131799 Number of partitions of n into parts that are squares or cubes.

Original entry on oeis.org

1, 1, 1, 1, 2, 2, 2, 2, 4, 5, 5, 5, 7, 8, 8, 8, 12, 14, 15, 15, 19, 21, 22, 22, 28, 33, 35, 37, 43, 48, 50, 52, 61, 69, 74, 78, 90, 98, 103, 107, 122, 135, 143, 152, 170, 186, 194, 203, 225, 247, 261, 275, 305, 330, 348, 362, 396, 429, 454, 477, 519, 561, 590, 618, 666, 717
Offset: 0

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Author

Reinhard Zumkeller, Jul 16 2007

Keywords

Comments

a(n) = A078635(n) for n < 32 = 2^5.

Examples

			a(10) = #{9+1, 8+1+1, 4+4+1+1, 4+1+1+1+1+1+1, 1+1+1+1+1+1+1+1+1+1} = 5.
		

Crossrefs

Programs

  • Mathematica
    nmax = 65; c2max = nmax^(1/2); c3max = nmax^(1/3);
    s = Flatten[{Table[n^2, {n, 1, c2max}]}~Join~{Table[n^3, {n, 1, c3max}]}];
    Table[Count[IntegerPartitions@n, x_ /; SubsetQ[s, x]], {n, 0, nmax}] (* Robert Price, Jul 31 2020 *)

Formula

G.f.: Product_{k>=1} (1 - x^(k^6)) / ((1 - x^(k^2)) * (1 - x^(k^3))). - Vaclav Kotesovec, Jan 12 2017

Extensions

a(0)=1 prepended by Ilya Gutkovskiy, Jan 11 2017

A280129 Expansion of Product_{k>=2} (1 + x^(k^2)).

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 2, 0, 0, 0, 2, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 2, 1, 0, 1, 3, 0, 0, 1, 1, 1, 0, 0, 1, 3, 0, 0, 2, 2, 0, 1, 2, 0, 1, 1, 2, 1
Offset: 0

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Author

Ilya Gutkovskiy, Dec 26 2016

Keywords

Comments

Number of partitions of n into distinct squares > 1.

Examples

			G.f. = 1 + x^4 + x^9 + x^13 + x^16 + x^20 + 2*x^25 + 2*x^29 + x^34 + x^36 + ...
a(25) = 2 because we have [25] and [16, 9].
		

Crossrefs

Programs

  • Mathematica
    nmax = 115; CoefficientList[Series[Product[1 + x^k^2, {k, 2, nmax}], {x, 0, nmax}], x]
  • PARI
    {a(n) = if(n < 0, 0, polcoeff( prod(k=2, sqrtint(n), 1 + x^k^2 + x*O(x^n)), n))}; /* Michael Somos, Dec 26 2016 */

Formula

G.f.: Product_{k>=2} (1 + x^(k^2)).
From Vaclav Kotesovec, Dec 26 2016: (Start)
a(n) = Sum_{k=0..n} (-1)^(n-k) * A033461(k).
a(n) + a(n-1) = A033461(n).
a(n) ~ A033461(n)/2.
(End)

A281541 Expansion of Sum_{i>=1} x^(i^2)/(1 - x^(i^2)) / Product_{j>=1} (1 - x^(j^2)).

Original entry on oeis.org

1, 2, 3, 5, 7, 9, 11, 15, 19, 23, 27, 34, 41, 47, 53, 64, 75, 86, 96, 113, 129, 145, 159, 182, 206, 229, 252, 284, 318, 349, 380, 423, 468, 513, 555, 616, 676, 736, 791, 869, 949, 1026, 1103, 1202, 1310, 1408, 1506, 1631, 1766, 1896, 2020, 2185, 2354, 2525, 2680, 2882, 3094, 3305, 3506, 3751, 4023, 4281, 4537
Offset: 1

Views

Author

Ilya Gutkovskiy, Jan 23 2017

Keywords

Comments

Total number of parts in all partitions of n into squares.
Convolution of A001156 and A046951.

Examples

			a(8) = 15 because we have [4, 4], [4, 1, 1, 1, 1], [1, 1, 1, 1, 1, 1, 1, 1] and 2 + 5 + 8 = 15.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1, [1, n], (s->
          `if`(s>n, 0, (p->p+[0, p[1]])(b(n-s, i))))(i^2)+b(n, i-1))
        end:
    a:= n-> b(n, isqrt(n))[2]:
    seq(a(n), n=1..70);  # Alois P. Heinz, Sep 19 2018
  • Mathematica
    nmax = 63; Rest[CoefficientList[Series[Sum[x^i^2/(1 - x^i^2), {i, 1, nmax}]/Product[1 - x^j^2, {j, 1, nmax}], {x, 0, nmax}], x]]

Formula

G.f.: Sum_{i>=1} x^(i^2)/(1 - x^(i^2)) / Product_{j>=1} (1 - x^(j^2)).
a(n) = Sum_{k=1..n} k * A243148(n,k). - Alois P. Heinz, Sep 19 2018
a(n) ~ exp(3 * 2^(-4/3) * zeta(3/2)^(2/3) * (Pi*n)^(1/3)) * sqrt(Pi/3) / (12*sqrt(n)). - Vaclav Kotesovec, Sep 15 2021

A284345 Number of partitions of n into squares dividing n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 1, 3, 2, 1, 1, 4, 1, 1, 1, 6, 1, 3, 1, 6, 1, 1, 1, 7, 2, 1, 4, 8, 1, 1, 1, 15, 1, 1, 1, 27, 1, 1, 1, 11, 1, 1, 1, 12, 6, 1, 1, 28, 2, 3, 1, 14, 1, 7, 1, 15, 1, 1, 1, 16, 1, 1, 8, 46, 1, 1, 1, 18, 1, 1, 1, 114, 1, 1, 4, 20, 1, 1, 1, 66, 11, 1, 1, 22, 1, 1, 1, 23, 1, 11, 1, 24, 1, 1, 1, 91, 1, 3, 12, 67
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 25 2017

Keywords

Examples

			a(8) = 3 because 8 has 4 divisors {1, 2, 4, 8} among which 2 are squares {1, 4} therefore we have [4, 4], [4, 1, 1, 1, 1] and [1, 1, 1, 1, 1, 1, 1, 1].
		

Crossrefs

Programs

  • Maple
    with(numtheory):
    a:= proc(n) option remember; local b, l; l, b:=
          sort(select(issqr, [divisors(n)[]])),
          proc(m, i) option remember; `if`(m=0, 1, `if`(i<1, 0,
            b(m, i-1)+`if`(l[i]>m, 0, b(m-l[i], i))))
          end; b(n, nops(l))
        end:
    seq(a(n), n=0..100);  # Alois P. Heinz, Mar 30 2017
  • Mathematica
    Join[{1}, Table[d = Divisors[n]; Coefficient[Series[Product[1/(1 - Boole[Mod[DivisorSigma[0, d[[k]]], 2] == 1] x^d[[k]]), {k, Length[d]}], {x, 0, n}], x, n], {n, 1, 100}]]

Formula

a(n) = [x^n] Product_{d^2|n} 1/(1 - x^(d^2)).
a(n) = 1 if n is a squarefree.
a(n) = 2 if n is a square of prime.

A285047 Expansion of Product_{k>=1} 1/(1-x^(k^2))^k.

Original entry on oeis.org

1, 1, 1, 1, 3, 3, 3, 3, 6, 9, 9, 9, 13, 19, 19, 19, 28, 37, 43, 43, 57, 69, 81, 81, 100, 132, 150, 160, 184, 236, 260, 280, 319, 391, 460, 490, 565, 657, 771, 811, 922, 1084, 1243, 1363, 1510, 1781, 1985, 2185, 2388, 2775, 3159, 3439, 3832, 4335, 4963, 5323
Offset: 0

Views

Author

Vaclav Kotesovec, Apr 15 2017

Keywords

Crossrefs

Programs

  • Mathematica
    nmax=100; CoefficientList[Series[Product[1/(1-x^(k^2))^k, {k,1,nmax}], {x,0,nmax}], x]

Formula

log(a(n)) ~ Pi*sqrt(n/3).

A324587 Heinz numbers of integer partitions of n into distinct perfect squares (A033461).

Original entry on oeis.org

1, 2, 7, 14, 23, 46, 53, 97, 106, 151, 161, 194, 227, 302, 311, 322, 371, 419, 454, 541, 622, 661, 679, 742, 827, 838, 1009, 1057, 1082, 1193, 1219, 1322, 1358, 1427, 1589, 1619, 1654, 1879, 2018, 2114, 2143, 2177, 2231, 2386, 2437, 2438, 2741, 2854, 2933
Offset: 1

Views

Author

Gus Wiseman, Mar 08 2019

Keywords

Comments

The Heinz number of an integer partition (y_1, ..., y_k) is prime(y_1) * ... * prime(y_k).
Also products of distinct elements of A011757.

Examples

			The sequence of terms together with their prime indices begins:
    1: {}
    2: {1}
    7: {4}
   14: {1,4}
   23: {9}
   46: {1,9}
   53: {16}
   97: {25}
  106: {1,16}
  151: {36}
  161: {4,9}
  194: {1,25}
  227: {49}
  302: {1,36}
  311: {64}
  322: {1,4,9}
  371: {4,16}
  419: {81}
  454: {1,49}
  541: {100}
		

Crossrefs

Programs

  • Mathematica
    Select[Range[1000],And@@Cases[FactorInteger[#],{p_,k_}:>k==1&&IntegerQ[Sqrt[PrimePi[p]]]]&]

A351982 Number of integer partitions of n into prime parts with prime multiplicities.

Original entry on oeis.org

1, 0, 0, 0, 1, 0, 2, 0, 0, 1, 3, 0, 1, 1, 3, 3, 3, 0, 1, 4, 5, 5, 3, 3, 5, 8, 5, 5, 6, 8, 8, 11, 7, 8, 10, 17, 14, 14, 12, 17, 17, 21, 18, 23, 20, 28, 27, 31, 27, 36, 32, 35, 37, 46, 41, 52, 45, 60, 58, 63, 59, 78, 71, 76, 81, 87, 80, 103, 107, 113, 114, 127
Offset: 0

Views

Author

Gus Wiseman, Mar 18 2022

Keywords

Examples

			The partitions for n = 4, 6, 10, 19, 20, 25:
  (22)  (33)   (55)     (55333)     (7733)       (55555)
        (222)  (3322)   (55522)     (77222)      (77722)
               (22222)  (3333322)   (553322)     (5533333)
                        (33322222)  (5522222)    (5553322)
                                    (332222222)  (55333222)
                                                 (55522222)
                                                 (333333322)
                                                 (3333322222)
		

Crossrefs

The version for just prime parts is A000607, ranked by A076610.
The version for just prime multiplicities is A055923, ranked by A056166.
For odd instead of prime we have A117958, ranked by A352142.
The constant case is A230595, ranked by A352519.
Allowing any multiplicity > 1 gives A339218, ranked by A352492.
These partitions are ranked by A346068.
The non-constant case is A352493, ranked by A352518.
A000040 lists the primes.
A001221 counts constant partitions of prime length, ranked by A053810.
A001694 lists powerful numbers, counted A007690, weak A052485.
A038499 counts partitions of prime length.
A101436 counts parts of prime signature that are themselves prime.
A112798 lists prime indices, reverse A296150, sum A056239.
A124010 gives prime signature, sorted A118914, sum A001222.
A257994 counts prime indices that are prime, nonprime A330944.

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n], And@@PrimeQ/@#&&And@@PrimeQ/@Length/@Split[#]&]],{n,0,30}]

A092362 Number of partitions of n^2 into squares greater than 1.

Original entry on oeis.org

1, 0, 1, 1, 2, 3, 5, 8, 11, 28, 44, 94, 167, 354, 643, 1314, 2412, 4792, 8981, 17374, 32566, 62008, 115702, 217040, 402396, 745795, 1372266, 2517983, 4595652, 8354350, 15125316, 27265107, 48972467, 87584837, 156119631, 277152178, 490437445, 864534950
Offset: 0

Views

Author

Reinhard Zumkeller, Mar 19 2004

Keywords

Comments

a(n) = A078134(A000290(n)).

Examples

			a(6) = 5: 6^2 = 36 = 16+16+4 = 16+4+4+4+4+4 = 9+9+9+9 = 4+4+4+4+4+4+4+4+4.
		

Crossrefs

Programs

  • Maple
    b:=proc(n, i) option remember; `if`(n=0, 1,
         `if`(i<2, 0, b(n, i-1) +`if`(i^2>n, 0, b(n-i^2, i))))
       end:
    a:= n-> b(n^2, n):
    seq(a(n), n=0..50);  # Alois P. Heinz, Apr 15 2013
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i<2, 0, b[n, i-1] + If[i^2>n, 0, b[n-i^2, i]]]]; a[n_] := b[n^2, n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Nov 11 2015, after Alois P. Heinz *)

Formula

a(n) ~ exp(3*Pi^(1/3) * Zeta(3/2)^(2/3) * n^(2/3) / 2^(4/3)) * Zeta(3/2)^(4/3) / (2^(11/3) * sqrt(3) * Pi^(5/6) * n^(11/3)). - Vaclav Kotesovec, Apr 10 2017

Extensions

Corrected a(0) and more terms from Alois P. Heinz, Apr 15 2013

A111178 Number of partitions of n into positive numbers one less than a square.

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 1, 2, 1, 1, 2, 1, 1, 2, 1, 2, 4, 1, 2, 4, 1, 2, 5, 2, 4, 5, 2, 5, 5, 2, 6, 7, 4, 6, 7, 5, 6, 8, 6, 8, 12, 6, 9, 13, 6, 10, 15, 8, 14, 15, 9, 16, 16, 10, 18, 21, 14, 19, 22, 16, 20, 24, 19, 25, 30, 20, 27, 33, 21, 29, 39, 26, 37, 40, 28, 42, 42, 31, 48
Offset: 0

Views

Author

Wouter Meeussen, Oct 22 2005

Keywords

Comments

Also limiting form of the number of representations of n into k positive squares for k decreasing from n to 1, or Table[Count[SumOfSquaresRepresentations[k,n], {a_,}/;a>0], {n,100,100}, {k,100,40,-1}]. (Franklin T. Adams-Watters: replacing k^2 ones by the value k^2 changes the count by k^2-1).
a(n) = A243148(2n,n). - Alois P. Heinz, May 30 2014

Crossrefs

Programs

  • Haskell
    a111178 = p $ tail a005563_list where
       p _          0 = 1
       p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m
    -- Reinhard Zumkeller, Apr 02 2014
  • Maple
    b:= proc(n, i) option remember;
          `if`(n=0, 1, `if`(i<2, 0, b(n, i-1)+
          `if`(i^2>n+1, 0, b(n+1-i^2, i))))
        end:
    a:= n-> b(n, isqrt(n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, May 30 2014
  • Mathematica
    nn = 100; CoefficientList[Series[Product[1/(1 - x^(k^2 - 1)), {k, 2, nn}], {x, 0, nn}], x] (* corrected by T. D. Noe, Feb 22 2012 *)
    b[n_, i_] := b[n, i] = If[n==0, 1, If[i<2, 0, b[n, i-1] + If[i^2>n+1, 0, b[n+1-i^2, i]]]]; a[n_] := b[n, Round[Sqrt[n]]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Feb 16 2017, after Alois P. Heinz *)

Formula

G.f.: Product_{k>=2} 1/(1-x^(k^2-1)).

A218494 Number of partitions of n^3 into squares.

Original entry on oeis.org

1, 1, 3, 21, 220, 2846, 41621, 670568, 11570877, 210605770, 3998468431, 78556582448, 1587757499592, 32866068149376, 694307793698105, 14927522659021682, 325895131806047690, 7211436102222542901, 161493494674514291108, 3655277488432342084426
Offset: 0

Views

Author

Reinhard Zumkeller, Oct 31 2012

Keywords

Examples

			n=2: number of partitions of 8 into parts of {1, 4}:
a(2) = #{4+4, 4+1+1+1+1, 8x1} = 3;
n=3: number of partitions of 27 into parts of  {1, 4, 9, 16, 25}:
a(3) = #{25+1+1, 16+9+1+1, 16+4+4+1, 16+4+5x1, 16+9x1, 9+9+9, 9+9+4+4+1, 9+9+4+5x1, 9+9+9x1, 9+4x4+1+1, 9+3x4+6x1, 9+4+4+10x1, 9+4+14x1, 9+18x1, 6x4+3x1, 5x4+7x1, 4x4+11x1, 3x4+15x1, 4+4+19x1, 4+23x1, 27x1} = 21.
		

Crossrefs

Programs

  • Haskell
    a218494 = p (tail a000290_list) . (^ 3) where
       p _          0 = 1
       p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m
  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1, 1,
           b(n, i-1)+`if`(i^2>n, 0, b(n-i^2, i)))
        end:
    a:= n-> b(n^3, isqrt(n^3)):
    seq(a(n), n=0..20);  # Alois P. Heinz, Nov 08 2012
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0 || i == 1, 1, b[n, i-1] + If[i^2>n, 0, b[n - i^2, i]]]; a[n_] := b[n^3, Sqrt[n^3] // Floor]; Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Nov 11 2015, after Alois P. Heinz *)

Formula

a(n) = A001156(A000578(n)).
a(n) ~ 3^(-1/2) * (4*Pi)^(-7/6) * Zeta(3/2)^(2/3) * n^(-7/2) * exp(2^(-4/3) * 3 * Pi^(1/3) * Zeta(3/2)^(2/3) * n) [after Hardy & Ramanujan]. - Vaclav Kotesovec, Apr 10 2017
a(n) = [x^(n^3)] Product_{k>=1} 1/(1 - x^(k^2)). - Ilya Gutkovskiy, Jan 29 2018

Extensions

Extended beyond a(7) by Alois P. Heinz, Nov 08 2012
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