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 11-20 of 20 results.

A300702 Number of compositions (ordered partitions) of n into parts that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 2, 0, 7, 2, 7, 7, 54, 2, 143, 33, 47, 30, 986, 23, 2583, 58, 1018, 828, 17710, 32, 23866, 3917, 14586, 1368, 317810, 248, 832039, 5902, 188953, 85038, 1505979, 602, 14930351, 393663, 2350986, 13524, 102334154, 16401, 267914295, 431711, 4438212, 8400611, 1836311902
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 11 2018

Keywords

Examples

			a(7) = 7 because we have [5, 2], [4, 3], [3, 4], [3, 2, 2], [2, 5], [2, 3, 2] and [2, 2, 3].
		

Crossrefs

Programs

  • Maple
    a:= proc(m) option remember; local b; b:= proc(n)
          option remember; `if`(n=0, 1, add(`if`(
          irem(m, j)=0, 0, b(n-j)), j=2..n)) end; b(m)
        end:
    seq(a(n), n=0..60);  # Alois P. Heinz, Mar 11 2018
  • Mathematica
    Table[SeriesCoefficient[1/(1 - Sum[Boole[Mod[n, k] != 0] x^k, {k, 1, n}]), {x, 0, n}], {n, 0, 47}]

A294266 Number of partitions of n into distinct squares that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 2, 1, 0, 0, 3, 0, 0, 0, 1, 1, 0, 0, 1, 3, 0, 0, 2, 2, 0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 3, 1, 0, 0, 2, 3, 0, 0, 1, 1, 0, 1, 2, 1, 1, 0, 2, 2, 0, 0, 3, 4
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 26 2017

Keywords

Examples

			a(29) = 2 because we have [25, 4] and [16, 9, 4].
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local P,k,x;
    P:= 1;
    for k from 2 to floor(sqrt(n)) do
      if n mod k^2 = 0 then next fi;
      P:= series(P*(1+x^(k^2)),x,n+1);
    od;
    coeff(P,x,n)
    end proc:
    map(f, [$0..200]); # Robert Israel, Apr 15 2024
  • Mathematica
    Table[SeriesCoefficient[Product[1 + Boole[Mod[n, k] > 0 && OddQ[DivisorSigma[0, k]]] x^k, {k, 1, n}], {x, 0, n}], {n, 0, 110}]

A300584 Number of partitions of n into distinct prime power parts (not including 1) that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 2, 1, 2, 1, 4, 1, 5, 2, 4, 3, 8, 2, 11, 4, 6, 6, 18, 3, 13, 10, 10, 8, 35, 7, 42, 9, 20, 24, 22, 10, 72, 33, 35, 11, 102, 21, 120, 29, 26, 65, 161, 16, 117, 56, 93, 52, 246, 43, 113, 36, 139, 160, 370, 39, 422, 208, 102, 62, 216, 110, 613, 145, 305, 130, 780, 57, 878
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 09 2018

Keywords

Examples

			a(9) = 2 because we have [7, 2] and [5, 4].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1 + Boole[Mod[n, k] != 0 && PrimePowerQ[k]] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 73}]

A339660 Number of strict integer partitions of n with no 1's and a part divisible by all the other parts.

Original entry on oeis.org

1, 0, 1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 4, 1, 3, 3, 3, 3, 5, 2, 5, 5, 4, 5, 7, 3, 5, 6, 5, 5, 9, 4, 7, 6, 6, 9, 11, 6, 9, 10, 9, 10, 12, 6, 11, 12, 10, 12, 16, 9, 15, 16, 12, 14, 18, 14, 16, 18, 14, 15, 22, 11, 16, 20, 13, 21, 23, 15, 21, 24, 21, 21, 31, 14, 24
Offset: 0

Views

Author

Gus Wiseman, Apr 19 2021

Keywords

Comments

Alternative name: Number of strict integer partitions of n with no 1's that are empty or have greatest part divisible by all the other parts.

Examples

			The a(n) partitions for n = 14, 12, 18, 24, 30, 39, 36:
  (14)     (12)    (18)      (24)        (30)        (39)          (36)
  (12,2)   (8,4)   (12,6)    (16,8)      (24,6)      (36,3)        (27,9)
  (8,4,2)  (9,3)   (15,3)    (18,6)      (25,5)      (26,13)       (30,6)
           (10,2)  (16,2)    (20,4)      (27,3)      (27,9,3)      (32,4)
                   (12,4,2)  (21,3)      (28,2)      (28,7,4)      (33,3)
                             (22,2)      (20,10)     (30,6,3)      (34,2)
                             (12,6,4,2)  (18,9,3)    (24,12,3)     (24,12)
                                         (24,4,2)    (24,8,4,3)    (24,8,4)
                                         (16,8,4,2)  (20,10,5,4)   (18,9,6,3)
                                                     (24,6,4,3,2)  (24,6,4,2)
                                                                   (20,10,4,2)
		

Crossrefs

The dual version is A098965 (non-strict: A083711).
The non-strict version is A339619 (Heinz numbers: complement of A343337).
The version with 1's allowed is A343347 (non-strict: A130689).
The case without a part dividing all the other parts is A343380.
A000009 counts strict partitions.
A000070 counts partitions with a selected part.
A015723 counts strict partitions with a selected part.
A018818 counts partitions into divisors (strict: A033630).
A167865 counts strict chains of divisors > 1 summing to n.

Programs

  • Mathematica
    Table[If[n==0,1,Length[Select[IntegerPartitions[n],FreeQ[#,1]&&UnsameQ@@#&&And@@IntegerQ/@(Max@@#/#)&]]],{n,0,30}]

A300586 Number of partitions of n into distinct squarefree parts that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 2, 1, 4, 2, 2, 4, 6, 2, 8, 4, 6, 6, 15, 4, 11, 10, 12, 8, 30, 3, 38, 24, 17, 24, 23, 14, 70, 36, 37, 23, 102, 8, 122, 49, 39, 80, 177, 38, 136, 54, 113, 101, 297, 60, 152, 102, 192, 226, 485, 28, 571, 312, 200, 390, 338, 84, 908, 393, 507, 104, 1229, 241, 1421
Offset: 0

Views

Author

Ilya Gutkovskiy, Mar 09 2018

Keywords

Examples

			a(14) = 2 because we have [11, 3] and [6, 5, 3].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[(1 + Boole[Mod[n, k] != 0 && SquareFreeQ[k]] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 73}]

A343348 Irregular triangle read by rows where T(n,k) is the number of strict integer partitions of n with least gap k.

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 2, 1, 0, 2, 1, 0, 1, 3, 1, 1, 0, 3, 2, 1, 0, 5, 2, 1, 0, 5, 3, 1, 0, 1, 7, 3, 1, 1, 0, 8, 4, 2, 1, 0, 10, 5, 2, 1, 0, 12, 6, 3, 1, 0, 15, 7, 3, 1, 0, 1, 17, 9, 4, 1, 1, 0, 21, 10, 4, 2, 1, 0, 25, 12, 6, 2, 1, 0, 29, 15, 6, 3, 1, 0, 35, 17, 8, 3, 1, 0
Offset: 0

Views

Author

Gus Wiseman, Apr 18 2021

Keywords

Comments

The least gap (or mex) of a partition is the least positive integer that is not a part.
Row lengths are chosen to be consistent with the non-strict case A264401.

Examples

			Triangle begins:
   1
   0   1
   1   0
   1   0   1
   1   1   0
   2   1   0
   2   1   0   1
   3   1   1   0
   3   2   1   0
   5   2   1   0
   5   3   1   0   1
   7   3   1   1   0
   8   4   2   1   0
  10   5   2   1   0
  12   6   3   1   0
  15   7   3   1   0   1
		

Crossrefs

Row sums are A000009.
Row lengths are A002024.
Column k = 1 is A025147.
Column k = 2 is A025148.
The non-strict version is A264401.
A000009 counts strict partitions.
A000041 counts partitions.
A000070 counts partitions with a selected part.
A006128 counts partitions with a selected position.
A015723 counts strict partitions with a selected part.
A257993 gives the least gap of the partition with Heinz number n.
A339564 counts factorizations with a selected factor.
A342050 ranks partitions with even least gap.
A342051 ranks partitions with odd least gap.

Programs

  • Mathematica
    mingap[q_]:=Min@@Complement[Range[If[q=={},0,Max[q]]+1],q];
    Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&mingap[#]==k&]],{n,0,15},{k,Round[Sqrt[2*(n+1)]]}]

A294141 Number of partitions of n into odd parts that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 2, 3, 0, 5, 5, 2, 7, 5, 1, 11, 14, 6, 9, 20, 5, 18, 33, 5, 43, 50, 12, 58, 17, 16, 91, 96, 26, 58, 146, 23, 183, 148, 11, 241, 285, 88, 187, 152, 98, 367, 537, 87, 177, 376, 179, 857, 983, 77, 1195, 1274, 79, 1596, 468, 290, 2117, 1887, 549, 460, 3064, 440
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 23 2017

Keywords

Examples

			a(13) = 2 because we have [7, 3, 3] and [5, 5, 3].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1/(1 - Boole[Mod[n, k] > 0 && OddQ[k]] x^k), {k, 1, n}], {x, 0, n}], {n, 0, 72}]

A294142 Number of partitions of n into distinct odd parts that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 2, 0, 3, 1, 2, 2, 3, 0, 4, 4, 4, 2, 6, 1, 6, 8, 4, 10, 12, 4, 12, 5, 7, 17, 17, 8, 14, 24, 9, 29, 24, 4, 33, 40, 25, 29, 28, 23, 45, 63, 23, 30, 52, 37, 84, 99, 26, 113, 112, 23, 143, 60, 57, 173, 143, 89, 70, 226, 87, 256, 256, 53, 245, 135, 127, 378, 233
Offset: 0

Views

Author

Ilya Gutkovskiy, Oct 23 2017

Keywords

Examples

			a(14) = 2 because we have [11, 3] and [9, 5].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[1 + Boole[Mod[n, k] > 0 && OddQ[k]] x^k, {k, 1, n}], {x, 0, n}], {n, 0, 80}]

A298262 Number of integer partitions of n using relatively prime non-divisors of n.

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 3, 1, 3, 2, 13, 1, 23, 7, 10, 8, 65, 5, 104, 11, 53, 53, 252, 8, 244, 124, 203, 67, 846, 22, 1237, 157, 636, 569, 1074, 51, 3659, 1140, 1827, 221, 7244, 236, 10086, 1162, 1844, 4169, 19195, 225, 17657, 2997
Offset: 1

Views

Author

Gus Wiseman, Jan 15 2018

Keywords

Examples

			The a(11) = 13 partitions: (65), (74), (83), (92), (443), (533), (542), (632), (722), (3332), (4322), (5222), (32222).
The a(14) = 7 partitions: (9 5), (11 3), (5 5 4), (6 5 3), (8 3 3), (4 4 3 3), (5 3 3 3).
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],And[GCD@@#===1,!Or@@(Divisible[n,#]&/@#)]&]],{n,50}]
  • PARI
    \\ here b(n) is A098743.
    b(n)={polcoef(1/prod(k=1, n, if(n%k, 1 - x^k, 1) + O(x*x^n)), n)}
    a(n)={sumdiv(n, d, moebius(d)*b(n/d))} \\ Andrew Howroyd, Aug 29 2018

Formula

a(n) = Sum_{d|n} mu(n/d) * A098743(d).

A332001 Number of compositions (ordered partitions) of n into distinct parts that do not divide n.

Original entry on oeis.org

1, 0, 0, 0, 0, 2, 0, 4, 2, 4, 4, 20, 2, 34, 14, 20, 14, 146, 8, 244, 22, 140, 202, 956, 16, 782, 596, 752, 216, 5786, 82, 10108, 640, 4016, 5200, 6028, 218, 53674, 14570, 19004, 980, 152810, 1786, 245884, 13588, 16534, 108382, 719156, 1494, 532532, 54316
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 04 2020

Keywords

Examples

			a(9) = 4 because we have [7, 2], [5, 4], [4, 5] and [2, 7].
		

Crossrefs

Programs

  • Maple
    a:= proc(n) local b, l; l, b:= numtheory[divisors](n),
          proc(m, i, p) option remember; `if`(m=0, p!, `if`(i<2, 0,
            b(m, i-1, p)+`if`(i>m or i in l, 0, b(m-i, i-1, p+1))))
          end; forget(b): b(n, n-1, 0)
        end:
    seq(a(n), n=0..63);  # Alois P. Heinz, Feb 04 2020
  • Mathematica
    a[n_] := Module[{b, l = Divisors[n]}, b[m_, i_, p_] := b[m, i, p] = If[m == 0, p!, If[i < 2, 0, b[m, i - 1, p] + If[i > m || MemberQ[l, i], 0, b[m - i, i - 1, p + 1]]]]; b[n, n - 1, 0]];
    a /@ Range[0, 63] (* Jean-François Alcover, Nov 30 2020, after Alois P. Heinz *)
Previous Showing 11-20 of 20 results.