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 1-5 of 5 results.

A064577 First differences of A064574.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 3, 0, 1, 1, 4, 0, 3, 0, 4, 1, 1, 0, 6, 1, 1, 2, 4, 0, 4, 0, 6, 1, 1, 1, 9, 0, 1, 1, 7, 0, 5, 0, 5, 3, 1, 0, 11, 1, 3, 1, 6, 0, 6, 1, 8, 1, 1, 0, 12, 0, 1, 3, 11, 1, 5, 0, 8, 1, 4, 0, 17, 0, 1, 3, 8, 1, 6, 0, 15, 4, 1, 0, 17, 1, 1, 1, 13, 0, 11, 1, 10, 1, 1, 1, 21, 0, 3, 4, 16
Offset: 1

Views

Author

Marc LeBrun, Sep 20 2001

Keywords

Comments

Apparently a(n)=0 when n+1 is prime. Diverges from A028422(n+1) at n=19.

Crossrefs

Formula

a(n) = A064574(n+1) - A064574(n). - Antti Karttunen, Feb 24 2020

A064573 Number of partitions of n into parts which are all powers of the same prime.

Original entry on oeis.org

0, 1, 2, 4, 5, 8, 9, 13, 15, 20, 21, 29, 30, 37, 40, 50, 51, 64, 65, 80, 84, 99, 100, 123, 125, 146, 151, 178, 179, 212, 213, 249, 255, 292, 295, 348, 349, 396, 404, 466, 467, 535, 536, 611, 622, 697, 698, 801, 803, 900, 910, 1025, 1026, 1152, 1156, 1298, 1311
Offset: 1

Views

Author

Marc LeBrun, Sep 20 2001

Keywords

Comments

The exponents cannot all be zero.

Examples

			a(5)=5: 5^1, 3^1+2*3^0, 2^2+1, 2*2^1+1, 2^1+3*2^0
From _Gus Wiseman_, Oct 10 2018: (Start)
The a(2) = 1 through a(9) = 15 integer partitions:
  (2)  (3)   (4)    (5)     (33)     (7)       (8)        (9)
       (21)  (22)   (41)    (42)     (331)     (44)       (81)
             (31)   (221)   (51)     (421)     (71)       (333)
             (211)  (311)   (222)    (511)     (422)      (441)
                    (2111)  (411)    (2221)    (2222)     (711)
                            (2211)   (4111)    (3311)     (4221)
                            (3111)   (22111)   (4211)     (22221)
                            (21111)  (31111)   (5111)     (33111)
                                     (211111)  (22211)    (42111)
                                               (41111)    (51111)
                                               (221111)   (222111)
                                               (311111)   (411111)
                                               (2111111)  (2211111)
                                                          (3111111)
                                                          (21111111)
(End)
		

Crossrefs

Programs

  • Mathematica
    Table[Length[Select[IntegerPartitions[n],PrimePowerQ[Times@@#]&]],{n,30}] (* Gus Wiseman, Oct 10 2018 *)
  • PARI
    first(n)={Vec(sum(k=2, n, if(isprime(k), 1/prod(r=0, logint(n,k), 1-x^(k^r) + O(x*x^n)) - 1/(1-x), 0)), -n)} \\ Andrew Howroyd, Dec 29 2017

Formula

G.f.: Sum_{k>=1} 1/(Product_{r>=0} 1-x^(prime(k)^r)) - 1/(1-x). - Andrew Howroyd, Dec 29 2017

Extensions

Name clarified by Andrew Howroyd, Dec 29 2017

A064572 Number of ways to partition n into parts which are all powers of some integer k.

Original entry on oeis.org

0, 1, 2, 5, 6, 10, 11, 17, 20, 26, 27, 38, 39, 47, 51, 65, 66, 82, 83, 102, 107, 123, 124, 153, 156, 178, 185, 216, 217, 254, 255, 297, 304, 342, 346, 408, 409, 457, 466, 535, 536, 609, 610, 690, 704, 780, 781, 895, 898, 998, 1009, 1130, 1131, 1263, 1268, 1418
Offset: 1

Views

Author

Marc LeBrun, Sep 20 2001

Keywords

Comments

Number of ways to partition n as Sum_i k^e_i, where the exponents e_i are not all 0.
The exponents cannot all be 0, e.g. a(2)=1 arises from 2^1, and does not include 2^0+2^0. - Shujing Lyu, Apr 23 2016

Examples

			a(4)=5: 4^1, 3^1+3^0, 2^2, 2*2^1, 2^1+2*2^0.
		

Crossrefs

Programs

  • PARI
    first(n)={Vec(sum(k=2, n, 1/prod(r=0, logint(n,k), 1-x^(k^r) + O(x*x^n)) - 1/(1-x), 0), -n)} \\ Andrew Howroyd, Dec 29 2017

Formula

G.f.: Sum_{k>=2} 1/(Product_{r>=0} 1-x^(k^r)) - 1/(1-x). - Andrew Howroyd, Dec 29 2017

A064575 First differences of A064572, where A064572(n) is the number of ways to partition n into parts which are all powers of some integer.

Original entry on oeis.org

1, 1, 3, 1, 4, 1, 6, 3, 6, 1, 11, 1, 8, 4, 14, 1, 16, 1, 19, 5, 16, 1, 29, 3, 22, 7, 31, 1, 37, 1, 42, 7, 38, 4, 62, 1, 48, 9, 69, 1, 73, 1, 80, 14, 76, 1, 114, 3, 100, 11, 121, 1, 132, 5, 150, 14, 142, 1, 193, 1, 168, 20, 213, 5, 223, 1, 247, 17, 247, 1, 319, 1, 286, 25, 339, 4, 355
Offset: 1

Views

Author

Marc LeBrun, Sep 20 2001

Keywords

Comments

Apparently a(n)=1 when n+1 is prime.

Crossrefs

Programs

A064576 First differences of A064573, where A064573(n) is the number of partitions of n into parts which are all powers of the same prime.

Original entry on oeis.org

1, 1, 2, 1, 3, 1, 4, 2, 5, 1, 8, 1, 7, 3, 10, 1, 13, 1, 15, 4, 15, 1, 23, 2, 21, 5, 27, 1, 33, 1, 36, 6, 37, 3, 53, 1, 47, 8, 62, 1, 68, 1, 75, 11, 75, 1, 103, 2, 97, 10, 115, 1, 126, 4, 142, 13, 141, 1, 181, 1, 167, 17, 202, 4, 218, 1, 239, 16, 243, 1, 302, 1, 285, 22, 331, 3, 349
Offset: 1

Views

Author

Marc LeBrun, Sep 20 2001

Keywords

Comments

Apparently a(n)=1 when n+1 is prime.

Crossrefs

Programs

Showing 1-5 of 5 results.