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 1-8 of 8 results.

A268443 a(n) = (A005705(n) - A268444(n))/4.

Original entry on oeis.org

0, 0, 0, 0, 1, 1, 1, 1, 3, 3, 3, 3, 6, 6, 6, 6, 11, 12, 13, 14, 17, 18, 19, 20, 25, 26, 27, 28, 35, 36, 37, 38, 49, 52, 55, 58, 64, 67, 70, 73, 82, 85, 88, 91, 103, 106, 109, 112, 130, 136, 142, 148, 158, 164, 170, 176, 190, 196, 202, 208, 226, 232, 238, 244
Offset: 0

Views

Author

Tom Edgar, Feb 04 2016

Keywords

Crossrefs

Programs

  • Sage
    def b(n):
        A=[1]
        for i in [1..n]:
            A.append(A[i-1] + A[i//4])
        return A[n]
    print([(b(n)-prod(x+1 for x in n.digits(4)))/4 for n in [0..63]])

Formula

Let b(0) = 1 and b(n) = b(n-1) + b(floor(n/4)) and let c(n) = Product_{i=0..k}(n_i+1) where n = Sum_{i=0..k}n_i*4^i is the base 4 representation of n. Then a(n) = (1/4)*(b(n) - c(n)).

A005704 Number of partitions of 3n into powers of 3.

Original entry on oeis.org

1, 2, 3, 5, 7, 9, 12, 15, 18, 23, 28, 33, 40, 47, 54, 63, 72, 81, 93, 105, 117, 132, 147, 162, 180, 198, 216, 239, 262, 285, 313, 341, 369, 402, 435, 468, 508, 548, 588, 635, 682, 729, 783, 837, 891, 954, 1017, 1080, 1152, 1224, 1296, 1377, 1458, 1539, 1632
Offset: 0

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Author

Keywords

Comments

Infinite convolution product of [1,2,3,3,3,3,3,3,3,3] aerated A000244 - 1 times, i.e., [1,2,3,3,3,3,3,3,3,3] * [1,0,0,2,0,0,3,0,0,3] * [1,0,0,0,0,0,0,0,0,2] * ... [Mats Granvik, Gary W. Adamson, Aug 07 2009]

References

  • R. K. Guy, personal communication.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Mathematica
    Fold[Append[#1, Total[Take[Flatten[Transpose[{#1, #1, #1}]], #2]]] &, {1}, Range[2, 55]] (* Birkas Gyorgy, Apr 18 2011 *)
    a[n_] := a[n] = If[n <= 2, n + 1, a[n - 1] + a[Floor[n/3]]]; Array[a, 101, 0] (* T. D. Noe, Apr 18 2011 *)
  • Python
    from functools import lru_cache
    @lru_cache(maxsize=None)
    def A005704(n): return A005704(n-1)+A005704(n//3) if n else 1 # Chai Wah Wu, Sep 21 2022

Formula

a(n) = a(n-1)+a(floor(n/3)).
Coefficient of x^(3*n) in prod(k>=0, 1/(1-x^(3^k))). Also, coefficient of x^n in prod(k>=0, 1/(1-x^(3^k)))/(1-x). - Benoit Cloitre, Nov 28 2002
a(n) mod 3 = binomial(2n, n) mod 3. - Benoit Cloitre, Jan 04 2004
Let T(x) be the g.f., then T(x)=(1-x^3)/(1-x)^2*T(x^3). [Joerg Arndt, May 12 2010]

Extensions

Formula and more terms from Henry Bottomley, Apr 30 2001

A005706 Number of partitions of 5n into powers of 5.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 9, 11, 13, 15, 18, 21, 24, 27, 30, 34, 38, 42, 46, 50, 55, 60, 65, 70, 75, 82, 89, 96, 103, 110, 119, 128, 137, 146, 155, 166, 177, 188, 199, 210, 223, 236, 249, 262, 275, 290, 305, 320, 335, 350, 368, 386, 404, 422, 440, 461, 482, 503, 524, 545
Offset: 0

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Author

Keywords

Comments

Euler transform of [2,0,0,0,1,0,0,0,0,...] with 1's at 5^n. - Michael Somos, Mar 16 2004
Partial sums of number of partitions of n into powers of 5. - Michael Somos, Mar 16 2004

References

  • R. K. Guy, personal communication.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Column k=5 of A292477.

Programs

  • Mathematica
    a[0] = 1; a[n_] := a[n] = a[n - 1] + a[Floor[n/5]]; Table[a@ n, {n, 0, 60}] (* Michael De Vlieger, Mar 25 2016 *)
  • PARI
    a(n)=if(n<1,n==0,a(n-1)+a(n\5))

Formula

a(n) = a(n-1) + a([n/5]).
a(n) = [x^(5*n)] Product_{k>=0} 1/(1 - x^(5^k)). - Ilya Gutkovskiy, Jun 05 2017

Extensions

Formula and more terms from Henry Bottomley, Apr 30 2001

A072720 Number of partitions of n into parts which are each powers of a single number (which may vary between partitions).

Original entry on oeis.org

1, 1, 2, 3, 5, 6, 10, 11, 15, 17, 23, 24, 34, 35, 43, 47, 57, 58, 73, 74, 91, 96, 112, 113, 139, 141, 163, 168, 197, 198, 235, 236, 272, 279, 317, 321, 378, 379, 427, 436, 501, 502, 575, 576, 653, 666, 742, 743, 851, 853, 952, 963, 1080, 1081, 1211, 1216, 1361
Offset: 0

Views

Author

Henry Bottomley, Jul 05 2002

Keywords

Comments

First differs from A322912 at a(12) = 34, A322912(12) = 33.

Examples

			a(6)=10 since 6 can be written as 6 (powers of 6), 5+1 (5), 4+1+1 (4 or 2), 3+3 (3), 3+1+1+1 (3), 4+2 (2), 2+2+2 (2), 2+2+1+1 (2), 2+1+1+1+1 (2) and 1+1+1+1+1+1 (powers of anything).
From _Gus Wiseman_, Jan 01 2019: (Start)
The a(1) = 1 through a(8) = 15 integer partitions:
  (1)  (2)   (3)    (4)     (5)      (6)       (7)        (8)
       (11)  (21)   (22)    (41)     (33)      (61)       (44)
             (111)  (31)    (221)    (42)      (331)      (71)
                    (211)   (311)    (51)      (421)      (422)
                    (1111)  (2111)   (222)     (511)      (611)
                            (11111)  (411)     (2221)     (2222)
                                     (2211)    (4111)     (3311)
                                     (3111)    (22111)    (4211)
                                     (21111)   (31111)    (5111)
                                     (111111)  (211111)   (22211)
                                               (1111111)  (41111)
                                                          (221111)
                                                          (311111)
                                                          (2111111)
                                                          (11111111)
(End)
		

Crossrefs

Programs

  • Mathematica
    radbase[n_]:=n^(1/GCD@@FactorInteger[n][[All,2]]);
    Table[Length[Select[IntegerPartitions[n],SameQ@@radbase/@DeleteCases[#,1]&]],{n,30}] (* Gus Wiseman, Jan 01 2019 *)

Formula

a(n) = a(n-1) + A072721(n). a(p) = a(p-1)+1 for p prime.

A292477 Square array A(n,k), n >= 0, k >= 2, read by antidiagonals: A(n,k) = [x^(k*n)] Product_{j>=0} 1/(1 - x^(k^j)).

Original entry on oeis.org

1, 1, 2, 1, 2, 4, 1, 2, 3, 6, 1, 2, 3, 5, 10, 1, 2, 3, 4, 7, 14, 1, 2, 3, 4, 6, 9, 20, 1, 2, 3, 4, 5, 8, 12, 26, 1, 2, 3, 4, 5, 7, 10, 15, 36, 1, 2, 3, 4, 5, 6, 9, 12, 18, 46, 1, 2, 3, 4, 5, 6, 8, 11, 15, 23, 60, 1, 2, 3, 4, 5, 6, 7, 10, 13, 18, 28, 74, 1, 2, 3, 4, 5, 6, 7, 9, 12, 15, 21, 33, 94
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 17 2017

Keywords

Comments

A(n,k) is the number of partitions of k*n into powers of k.

Examples

			Square array begins:
   1,  1,  1,  1,  1,  1, ...
   2,  2,  2,  2,  2,  2, ...
   4,  3,  3,  3,  3,  3, ...
   6,  5,  4,  4,  4,  4, ...
  10,  7,  6,  5,  5,  5, ...
  14,  9,  8,  7,  6,  6, ...
		

Crossrefs

Columns k=2..5 give A000123, A005704, A005705, A005706.
Mirror of A089688 (excluding the first row).

Programs

  • Mathematica
    Table[Function[k, SeriesCoefficient[Product[1/(1 - x^k^i), {i, 0, n}], {x, 0, k n}]][j - n + 2], {j, 0, 12}, {n, 0, j}] // Flatten

A089688 Table T(n,k), n>=0 and k>=1, read by antidiagonals; the k-th row is defined by : partitions of k*n into powers of k (with T(0,k) = 1).

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 4, 2, 1, 1, 6, 3, 2, 1, 1, 10, 5, 3, 2, 1, 1, 14, 7, 4, 3, 2, 1, 1, 20, 9, 6, 4, 3, 2, 1, 1, 26, 12, 8, 5, 4, 3, 2, 1, 1, 36, 15, 10, 7, 5, 4, 3, 2, 1, 1, 46, 18, 12, 9, 6, 5, 4, 3, 2, 1, 1, 60, 23, 15, 11, 8, 6, 5, 4, 3, 2, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 05 2004

Keywords

Examples

			Row k = 1 : 1, 1, 1, 1,  1,  1,  1,  1,  1,  1,  1,  1, ... (see A000012).
Row k = 2 : 1, 2, 4, 6, 10, 14, 20, 26, 36, 46, 60, 74, ... (see A000123).
Row k = 3 : 1, 2, 3, 5,  7,  9, 12, 15, 18, 23, 28, 33, ... (see A005704).
Row k = 4 : 1, 2, 3, 4,  6,  8, 10, 12, 15, 18, 21, 24, ... (see A005705).
Row k = 5 : 1, 2, 3, 4,  5,  7,  9, 11, 13, 15, 18, 21, ... (see A005706).
		

A309678 G.f. A(x) satisfies: A(x) = A(x^4) / (1 - x)^2.

Original entry on oeis.org

1, 2, 3, 4, 7, 10, 13, 16, 22, 28, 34, 40, 50, 60, 70, 80, 97, 114, 131, 148, 175, 202, 229, 256, 296, 336, 376, 416, 472, 528, 584, 640, 718, 796, 874, 952, 1058, 1164, 1270, 1376, 1516, 1656, 1796, 1936, 2116, 2296, 2476, 2656, 2886, 3116, 3346, 3576, 3866, 4156, 4446, 4736, 5096
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 12 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 56; A[] = 1; Do[A[x] = A[x^4]/(1 - x)^2 + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    nmax = 56; CoefficientList[Series[Product[1/(1 - x^(4^k))^2, {k, 0, Floor[Log[4, nmax]] + 1}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=0} 1/(1 - x^(4^k))^2.

A272270 Positive integers n where the number of parts function on the set of 4-ary partitions of n is equidistributed mod 4.

Original entry on oeis.org

12, 13, 14, 15, 28, 29, 30, 31, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 76, 77, 78, 79, 92, 93, 94, 95, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 140, 141, 142, 143
Offset: 1

Views

Author

Tom Edgar, Apr 28 2016

Keywords

Comments

An integer n is in the list if and only if n_i=3 for some index i>0 where n = Sum_{i>=0}n_i4^i is the base 4 representation of n.

Examples

			There are four 4-ary partitions of 12: one has 12 parts (1+1+1+1+1+1+1+1+1+1+1+1), one has 3 parts (4+4+4), one has 9 parts (4+1+1+1+1+1+1+1+1), and one has 6 parts (4+4+1+1+1+1); thus, modulo 4, the number of parts function is equidistributed mod 4 and so 12 is a term.
There are six 4-ary partitions of 16 so the number of parts function cannot be equidistributed mod 4. Thus, 16 is not a term.
		

Crossrefs

Programs

  • Sage
    [n for n in [1..150] if 3 in n.digits(4)[1:]]
Showing 1-8 of 8 results.