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 1-7 of 7 results.

A121919 Least m such that partition number of m modulo m (=A093952(m)) is n.

Original entry on oeis.org

1, 4, 5, 9, 74, 6, 8, 16, 17, 14, 13, 15, 22, 23, 1402, 19, 41, 69, 26, 232, 61, 617, 28, 38, 30, 205, 50, 196, 65, 32, 175, 56, 96, 381, 45, 140, 57, 104, 59, 51, 119, 795, 262, 117, 78, 88, 86, 60, 106, 812, 113, 63, 81, 90, 229, 72, 66, 209, 71, 68, 352, 178, 64, 354
Offset: 0

Views

Author

Zak Seidov, Sep 02 2006

Keywords

Examples

			a(3)=9 because partition number of 9 is 30 == 3 modulo 9,
a(5)=74 because partition number of 74 is 7089500 == 5 modulo 74, etc.
		

Crossrefs

Programs

  • Mathematica
    t = Table[0, {10000}]; k = 1; While[k < 475000, a = Mod[ PartitionsP@k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t (* Robert G. Wilson v, Jul 16 2009 *)

Extensions

b-file extended by Max Alekseyev, Jun 13 2011, May 19 2014

A051177 Perfectly partitioned numbers: numbers k that divide the number of partitions p(k).

Original entry on oeis.org

1, 2, 3, 124, 158, 342, 693, 1896, 3853, 4434, 5273, 8640, 14850, 17928, 110516, 178984, 274534
Offset: 1

Views

Author

M.A. Muller (mam(AT)land.sun.ac.za)

Keywords

Comments

Are there infinitely many perfectly partitioned numbers? Does there exist some k > 3 for which p(k) is a perfectly partitioned number?
No other terms below 10^8. - Max Alekseyev, May 19 2014
A probabilistic analysis suggests that there are infinitely many terms. - Franklin T. Adams-Watters, Oct 07 2018

Examples

			a(4) = 124 because p(124) = 2841940500 is divisible by 124.
a(7) = 693 because partition number of 693 is 43397921522754943172592795 = 693*62623263380598763596815.
		

References

  • Problem 2464, Journal of Recreational Mathematics 29(4), p. 304.
  • Solution to problem 2464 "Perfect Partitions", Journal of Recreational Mathematics 30(4), pp. 294-295, 1999-2000.

Crossrefs

Cf. A000041.
Cf. A093952 = partition number A000041(n) mod n.

Programs

  • Mathematica
    Do[ If[ Mod[ PartitionsP@n, n] == 0, Print@n], {n, 250000}] (* Robert G. Wilson v *)
    Select[Range[275000],Divisible[PartitionsP[#],#]&] (* Harvey P. Dale, Aug 21 2013~ *)
  • PARI
    for(n=1,20000,if(numbpart(n)%n==0,print1(n,","))) \\ Klaus Brockhaus, Sep 06 2006

Extensions

More terms from Don Reble, Jul 26 2002

A128836 Numbers k such that partition number p(k) == 1 (mod k).

Original entry on oeis.org

1, 4, 7, 11, 54, 55, 115, 146, 157, 234, 239, 951, 272732, 419192, 7626972, 38355152
Offset: 1

Views

Author

Keywords

Comments

Numbers k such that A093952(k) = 1.
There are no other terms below 10^8. - Max Alekseyev, May 19 2014

Crossrefs

Extensions

a(16) from Max Alekseyev, Jan 15 2013

A094252 a(n) = partition(n) mod prime(n).

Original entry on oeis.org

1, 2, 3, 5, 7, 11, 15, 3, 7, 13, 25, 3, 19, 6, 35, 19, 2, 19, 21, 59, 62, 54, 10, 62, 18, 12, 23, 80, 96, 67, 111, 96, 5, 78, 132, 8, 128, 98, 123, 143, 12, 141, 40, 98, 90, 88, 53, 93, 97, 187, 186, 47, 2, 117, 241, 34, 27, 51, 266, 108, 259, 115, 278, 30, 281, 227, 244, 141
Offset: 1

Views

Author

Gary W. Adamson, Apr 25 2004

Keywords

Comments

Indices n such that a(n)=0 (i.e., prime(n) divides partition(n)) are listed in A245662. - Max Alekseyev, Jul 27 2014

Examples

			a(10) = 13: partition(10) = 42, prime(10) = 29. 42 mod 29 = 13.
		

Crossrefs

Programs

  • Mathematica
    Table[ Mod[ PartitionsP[n], Prime[n]], {n, 70}] (* Robert G. Wilson v, Apr 28 2004 *)

Extensions

Edited by Robert G. Wilson v, Apr 28 2004

A121015 Numbers n such that partition number p(n) == 14 (mod n).

Original entry on oeis.org

1, 2, 8, 1402, 3579, 4111, 5289, 6383, 6467, 15146, 32141, 41910, 82849, 110088, 127531, 185114, 1320338, 1467242, 5739729, 22507473, 32494198
Offset: 1

Views

Author

Zak Seidov, Sep 02 2006

Keywords

Comments

No other terms below 10^8. - Max Alekseyev, May 19 2014

Examples

			Partition number of 8 is 22 = 1*8 + 14, hence 8 is a term.
Partition number of 1402 is 52435757789401123913939450130086135644 = 37400683159344596229628709079947315*1402 + 14, hence 1402 is a term.
		

Crossrefs

Programs

  • Mathematica
    Do[ If[ Mod[ PartitionsP@n - 14, n] == 0, Print@n], {n, 731000}] (* Robert G. Wilson v, Sep 14 2006 *)
  • PARI
    for(n=1,200000,if((numbpart(n)-14)%n==0,print1(n,","))) \\ Klaus Brockhaus, Sep 07 2006

Extensions

Edited, corrected and extended (a(1) to a(3), a(11) to a(16)) by Klaus Brockhaus, Sep 07 2006
Rechecked by Klaus Brockhaus, Mar 17 2007
a(17)-a(19) from Ryan Propper, Mar 17 2007
a(20) from Max Alekseyev, Dec 28 2011
a(21) from Max Alekseyev, Jan 15 2013

A203023 Integers n dividing A000041(n)+1.

Original entry on oeis.org

1, 6, 156, 305, 484, 1219, 322733, 14343797, 58460571, 68355787
Offset: 1

Views

Author

Max Alekseyev, Dec 27 2011

Keywords

Comments

No other terms below 10^8.

Crossrefs

A363252 a(n) = gcd(A000041(n), A000009(n)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 5, 2, 2, 2, 4, 1, 1, 1, 1, 1, 1, 1, 2, 1, 4, 1, 1, 1, 2, 3, 2, 2, 1, 4, 2, 3, 7, 2, 3, 1, 1, 1, 1, 21, 21, 2, 1, 1, 2, 6, 14, 3, 1, 2, 1, 1, 1, 1, 2, 1, 3, 4, 4, 17, 1, 2, 1, 2, 2, 4, 1, 3, 5, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 4, 1, 1, 1, 2, 11, 2
Offset: 0

Views

Author

Vaclav Kotesovec, May 23 2023, inspired by Zhi-Wei Sun

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1, add(b(n-j)*add(
         `if`(d::odd, d, 0), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    a:= n-> igcd(b(n), combinat[numbpart](n)):
    seq(a(n), n=0..120);  # Alois P. Heinz, May 23 2023
  • Mathematica
    Table[GCD[PartitionsP[n], PartitionsQ[n]], {n, 0, 100}]
Showing 1-7 of 7 results.