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 1-4 of 4 results.

A225323 Numbers n such that 11n is a partition number.

Original entry on oeis.org

1, 2, 7, 16, 21, 27, 35, 57, 72, 178, 338, 415, 622, 759, 1353, 1967, 2365, 2835, 4053, 4834, 5751, 15775, 18566, 21813, 25599, 35105, 47893, 65020, 75620, 101955, 118196, 158330, 490253, 644500, 738024, 1102924, 1636757, 1864205, 2121679, 2413060, 2742487, 3535243, 8424520, 10737664, 13654376, 27709215, 31120519
Offset: 1

Views

Author

Omar E. Pol, May 05 2013

Keywords

Examples

			2 is in the sequence because 11*2 = 22 and 22 is a partition number: p(8) = A000041(8) = 22.
		

Crossrefs

Programs

  • Mathematica
    Select[PartitionsP[Range[100]], Mod[#, 11] == 0 &]/11 (* T. D. Noe, May 05 2013 *)

Formula

a(j) = A225361(j)/11.

Extensions

a(11)-a(47) from R. J. Mathar, May 05 2013

A243935 Numbers m such that 5 divides A000041(m).

Original entry on oeis.org

4, 7, 9, 14, 18, 19, 23, 24, 27, 29, 34, 38, 39, 44, 49, 54, 58, 59, 61, 64, 66, 68, 69, 71, 74, 79, 82, 84, 89, 94, 97, 99, 103, 104, 109, 114, 119, 120, 124, 127, 128, 129, 130, 134, 136, 139, 140, 142, 144, 149, 154, 159, 163, 164, 165, 169, 170, 173, 174
Offset: 1

Views

Author

Bruno Berselli, Jun 15 2014

Keywords

Crossrefs

Numbers m such that k divides A000041(m), where k is prime: A001560 (k=2), A083214 (k=3), this sequence (k=5), A243936 (k=7), A027827 (k=11), A071750 (k=13). For k composite: A237278 (k=4), A035700 (k=12).

Programs

  • Magma
    [n: n in [1..200] | IsZero(NumberOfPartitions(n) mod 5)];
    
  • Mathematica
    Select[Range[200], Mod[PartitionsP[#], 5] == 0 &]
  • PARI
    is(n)=numbpart(n)%5==0 \\ Charles R Greathouse IV, Apr 08 2015
  • Sage
    # From Peter Luschny in A000041
    @CachedFunction
    def A000041(n):
        if n == 0: return 1
        S = 0; J = n-1; k = 2
        while 0 <= J:
            T = A000041(J)
            S = S+T if is_odd(k//2) else S-T
            J -= k if is_odd(k) else k//2
            k += 1
        return S
    [n for n in (0..200) if mod(A000041(n),5) == 0]
    

A071750 Numbers k such that 13 divides p(k), the k-th partition number, A000041(k).

Original entry on oeis.org

28, 62, 84, 94, 129, 136, 173, 180, 197, 213, 219, 226, 227, 237, 240, 264, 294, 311, 318, 326, 335, 338, 357, 358, 389, 418, 453, 458, 473, 482, 484, 486, 508, 529, 538, 542, 562, 600, 635, 644, 668, 670, 684, 697, 699, 713, 714, 727, 742, 747, 751, 778
Offset: 1

Views

Author

Benoit Cloitre, Jun 24 2002

Keywords

Crossrefs

Cf. A000041, A027827, A243935 (see crossrefs).

Programs

  • Mathematica
    Select[ Range[800], Mod[ PartitionsP[ # ], 13] == 0 &]
  • PARI
    \ps800 for(n=0,600,if(polcoeff(1/eta(x),n,x)%13==0,print1(n,",")))
    
  • PARI
    is(n)=numbpart(n)%13==0 \\ Charles R Greathouse IV, Apr 08 2015

Extensions

Edited by Robert G. Wilson v, Jun 27 2002

A243936 Numbers m such that 7 divides A000041(m).

Original entry on oeis.org

5, 10, 11, 12, 16, 18, 19, 24, 26, 27, 33, 37, 39, 40, 41, 47, 48, 52, 53, 54, 55, 61, 68, 75, 76, 82, 83, 89, 96, 97, 103, 110, 111, 117, 124, 125, 131, 138, 140, 145, 147, 152, 159, 166, 170, 173, 177, 180, 187, 191, 194, 201, 208, 213, 215, 222, 225, 229, 232
Offset: 1

Views

Author

Bruno Berselli, Jun 15 2014

Keywords

Crossrefs

Numbers m such that k divides A000041(m), where k is prime: A001560 (k=2), A083214 (k=3), A243935 (k=5), this sequence (k=7), A027827 (k=11), A071750 (k=13). For k composite: A237278 (k=4), A035700 (k=12).

Programs

  • Magma
    [n: n in [1..250] | IsZero(NumberOfPartitions(n) mod 7)];
    
  • Mathematica
    Select[Range[250], Mod[PartitionsP[#], 7] == 0 &]
  • PARI
    is(n)=numbpart(n)%7==0 \\ Charles R Greathouse IV, Apr 08 2015
  • Sage
    # From Peter Luschny in A000041
    @CachedFunction
    def A000041(n):
        if n == 0: return 1
        S = 0; J = n-1; k = 2
        while 0 <= J:
            T = A000041(J)
            S = S+T if is_odd(k//2) else S-T
            J -= k if is_odd(k) else k//2
            k += 1
        return S
    [n for n in (0..250) if mod(A000041(n),7) == 0]
    
Showing 1-4 of 4 results.