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 1-10 of 14 results. Next

A000607 Number of partitions of n into prime parts.

Original entry on oeis.org

1, 0, 1, 1, 1, 2, 2, 3, 3, 4, 5, 6, 7, 9, 10, 12, 14, 17, 19, 23, 26, 30, 35, 40, 46, 52, 60, 67, 77, 87, 98, 111, 124, 140, 157, 175, 197, 219, 244, 272, 302, 336, 372, 413, 456, 504, 557, 614, 677, 744, 819, 899, 987, 1083, 1186, 1298, 1420, 1552, 1695, 1850, 2018, 2198, 2394, 2605, 2833, 3079, 3344
Offset: 0

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Author

Keywords

Comments

a(n) gives the number of values of k such that A001414(k) = n. - Howard A. Landman, Sep 25 2001
Let W(n) = {prime p: There is at least one number m whose spf is p, and sopfr(m) = n}. Let V(n,p) = {m: sopfr(m) = n, p belongs to W(n)}. Then a(n) = sigma(|V(n,p)|). E.g.: W(10) = {2,3,5}, V(10,2) = {30,32,36}, V(10,3) = {21}, V(10,5) = {25}, so a(10) = 3+1+1 = 5. - David James Sycamore, Apr 14 2018
From Gus Wiseman, Jan 18 2020: (Start)
Also the number of integer partitions such that the sum of primes indexed by the parts is n. For example, the sum of primes indexed by the parts of the partition (3,2,1,1) is prime(3)+prime(2)+prime(1)+prime(1) = 12, so (3,2,1,1) is counted under a(12). The a(2) = 1 through a(14) = 10 partitions are:
1 2 11 3 22 4 32 41 33 5 43 6 44
21 111 31 221 222 42 322 331 51 52
211 1111 311 321 411 421 332 431
2111 2211 2221 2222 422 3222
11111 3111 3211 3221 3311
21111 22111 4111 4211
111111 22211 22221
31111 32111
211111 221111
1111111
(End)

Examples

			n = 10 has a(10) = 5 partitions into prime parts: 10 = 2 + 2 + 2 + 2 + 2 = 2 + 2 + 3 + 3 = 2 + 3 + 5 = 3 + 7 = 5 + 5.
n = 15 has a(15) = 12 partitions into prime parts: 15 = 2 + 2 + 2 + 2 + 2 + 2 + 3 = 2 + 2 + 2 + 3 + 3 + 3 = 2 + 2 + 2 + 2 + 2 + 5 = 2 + 2 + 2 + 2 + 7 = 2 + 2 + 3 + 3 + 5 = 2 + 3 + 5 + 5 = 2 + 3 + 3 + 7 = 2 + 2 + 11 = 2 + 13 = 3 + 3 + 3 + 3 + 3 = 3 + 5 + 7 = 5 + 5 + 5.
		

References

  • R. Ayoub, An Introduction to the Analytic Theory of Numbers, Amer. Math. Soc., 1963; see p. 203.
  • Mohammad K. Azarian, A Generalization of the Climbing Stairs Problem, Mathematics and Computer Education, Vol. 31, No. 1, pp. 24-28, Winter 1997. MathEduc Database (Zentralblatt MATH, 1997c.01891).
  • B. C. Berndt and B. M. Wilson, Chapter 5 of Ramanujan's second notebook, pp. 49-78 of Analytic Number Theory (Philadelphia, 1980), Lect. Notes Math. 899, 1981, see Entry 29.
  • D. M. Burton, Elementary Number Theory, 5th ed., McGraw-Hill, 2002.
  • L. M. Chawla and S. A. Shad, On a trio-set of partition functions and their tables, J. Natural Sciences and Mathematics, 9 (1969), 87-96.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

G.f. = 1 / g.f. for A046675. See A046113 for the ordered (compositions) version.
Row sums of array A116865 and of triangle A261013.
Column sums of A331416.
Partitions whose Heinz number is divisible by their sum of primes are A330953.
Partitions of whose sum of primes is divisible by their sum are A331379.

Programs

  • Haskell
    a000607 = p a000040_list where
       p _      0 = 1
       p ks'@(k:ks) m = if m < k then 0 else p ks' (m - k) + p ks m
    -- Reinhard Zumkeller, Aug 05 2012
    
  • Magma
    [1] cat [#RestrictedPartitions(n,{p:p in PrimesUpTo(n)}): n in [1..100]]; // Marius A. Burtea, Jan 02 2019
  • Maple
    with(gfun):
    t1:=mul(1/(1-q^ithprime(n)),n=1..51):
    t2:=series(t1,q,50):
    t3:=seriestolist(t2); # fixed by Vaclav Kotesovec, Sep 14 2014
  • Mathematica
    CoefficientList[ Series[1/Product[1 - x^Prime[i], {i, 1, 50}], {x, 0, 50}], x]
    f[n_] := Length@ IntegerPartitions[n, All, Prime@ Range@ PrimePi@ n]; Array[f, 57] (* Robert G. Wilson v, Jul 23 2010 *)
    Table[Length[Select[IntegerPartitions[n],And@@PrimeQ/@#&]],{n,0,60}] (* Harvey P. Dale, Apr 22 2012 *)
    a[n_] := a[n] = If[PrimeQ[n], 1, 0]; c[n_] := c[n] = Plus @@ Map[# a[#] &, Divisors[n]]; b[n_] := b[n] = (c[n] + Sum[c[k] b[n - k], {k, 1, n - 1}])/n; Table[b[n], {n, 1, 20}] (* Thomas Vogler, Dec 10 2015: Uses Euler transform, caches computed values, faster than IntegerPartitions[] function. *)
    nmax = 100; pmax = PrimePi[nmax]; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 0; poly[[3]] = -1; Do[p = Prime[k]; Do[poly[[j + 1]] -= poly[[j + 1 - p]], {j, nmax, p, -1}];, {k, 2, pmax}]; s = Sum[poly[[k + 1]]*x^k, {k, 0, Length[poly] - 1}]; CoefficientList[Series[1/s, {x, 0, nmax}], x] (* Vaclav Kotesovec, Jan 11 2021 *)
  • PARI
    N=66;x='x+O('x^N); Vec(1/prod(k=1,N,1-x^prime(k))) \\ Joerg Arndt, Sep 04 2014
    
  • Python
    from sympy import primefactors
    l = [1, 0]
    for n in range(2, 101):
        l.append(sum(sum(primefactors(k)) * l[n - k] for k in range(1, n + 1)) // n)
    l  # Indranil Ghosh, Jul 13 2017
    
  • Sage
    [Partitions(n, parts_in=prime_range(n + 1)).cardinality() for n in range(100)]  # Giuseppe Coppoletta, Jul 11 2016
    

Formula

Asymptotically a(n) ~ exp(2 Pi sqrt(n/log n) / sqrt(3)) (Ayoub).
a(n) = (1/n)*Sum_{k=1..n} A008472(k)*a(n-k). - Vladeta Jovovic, Aug 27 2002
G.f.: 1/Product_{k>=1} (1-x^prime(k)).
See the partition arrays A116864 and A116865.
From Vaclav Kotesovec, Sep 15 2014 [Corrected by Andrey Zabolotskiy, May 26 2017]: (Start)
It is surprising that the ratio of the formula for log(a(n)) to the approximation 2 * Pi * sqrt(n/(3*log(n))) exceeds 1. For n=20000 the ratio is 1.00953, and for n=50000 (using the value from Havermann's tables) the ratio is 1.02458, so the ratio is increasing. See graph above.
A more refined asymptotic formula is found by Vaughan in Ramanujan J. 15 (2008), pp. 109-121, and corrected by Bartel et al. (2017): log(a(n)) = 2*Pi*sqrt(n/(3*log(n))) * (1 - log(log(n))/(2*log(n)) + O(1/log(n))).
See Bartel, Bhaduri, Brack, Murthy (2017) for a more complete asymptotic expansion. (End)
G.f.: 1 + Sum_{i>=1} x^prime(i) / Product_{j=1..i} (1 - x^prime(j)). - Ilya Gutkovskiy, May 07 2017
a(n) = A184198(n) + A184199(n). - Vaclav Kotesovec, Jan 11 2021

A000586 Number of partitions of n into distinct primes.

Original entry on oeis.org

1, 0, 1, 1, 0, 2, 0, 2, 1, 1, 2, 1, 2, 2, 2, 2, 3, 2, 4, 3, 4, 4, 4, 5, 5, 5, 6, 5, 6, 7, 6, 9, 7, 9, 9, 9, 11, 11, 11, 13, 12, 14, 15, 15, 17, 16, 18, 19, 20, 21, 23, 22, 25, 26, 27, 30, 29, 32, 32, 35, 37, 39, 40, 42, 44, 45, 50, 50, 53, 55, 57, 61, 64, 67, 70, 71, 76, 78, 83, 87, 89, 93, 96
Offset: 0

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Author

Keywords

Examples

			n=16 has a(16) = 3 partitions into distinct prime parts: 16 = 2+3+11 = 3+13 = 5+11.
		

References

  • H. Gupta, Certain averages connected with partitions. Res. Bull. Panjab Univ. no. 124 1957 427-430.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence in two entries, N0004 and N0039).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A000041, A070215, A000607 (parts may repeat), A112022, A000009, A046675, A319264, A319267.

Programs

  • Haskell
    a000586 = p a000040_list where
       p _  0 = 1
       p (k:ks) m = if m < k then 0 else p ks (m - k) + p ks m
    -- Reinhard Zumkeller, Aug 05 2012
    
  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          b(n, i-1)+`if`(ithprime(i)>n, 0, b(n-ithprime(i), i-1))))
        end:
    a:= n-> b(n, numtheory[pi](n)):
    seq(a(n), n=0..100);  # Alois P. Heinz, Nov 15 2012
  • Mathematica
    CoefficientList[Series[Product[(1+x^Prime[k]), {k, 24}], {x, 0, Prime[24]}], x]
    b[n_, i_] := b[n, i] = If[n == 0, 1, If[i < 1, 0, b[n, i-1] + If[Prime[i] > n, 0, b[n - Prime[i], i-1]]]]; a[n_] := b[n, PrimePi[n]]; Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Apr 09 2014, after Alois P. Heinz *)
    nmax = 100; pmax = PrimePi[nmax]; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 0; poly[[3]] = 1; Do[p = Prime[k]; Do[poly[[j]] += poly[[j - p]], {j, nmax + 1, p + 1, -1}];, {k, 2, pmax}]; poly (* Vaclav Kotesovec, Sep 20 2018 *)
  • PARI
    a(n,k=n)=if(n<1, !n, my(s);forprime(p=2,k,s+=a(n-p,p-1));s) \\ Charles R Greathouse IV, Nov 20 2012
    
  • Python
    from sympy import isprime, primerange
    from functools import cache
    @cache
    def a(n, k=None):
        if k == None: k = n
        if n < 1: return int(n == 0)
        return sum(a(n-p, p-1) for p in primerange(1, k+1))
    print([a(n) for n in range(83)]) # Michael S. Branicky, Sep 03 2021 after Charles R Greathouse IV

Formula

G.f.: Product_{k>=1} (1+x^prime(k)).
a(n) = A184171(n) + A184172(n). - R. J. Mathar, Jan 10 2011
a(n) = Sum_{k=0..A024936(n)} A219180(n,k). - Alois P. Heinz, Nov 13 2012
log(a(n)) ~ Pi*sqrt(2*n/(3*log(n))) [Roth and Szekeres, 1954]. - Vaclav Kotesovec, Sep 13 2018

Extensions

Entry revised by N. J. A. Sloane, Jun 10 2012

A292561 Expansion of Product_{k>=1} (1 - mu(k)^2*x^k), where mu() is the Moebius function (A008683).

Original entry on oeis.org

1, -1, -1, 0, 1, 0, -1, 1, 2, 0, -3, 0, 2, 0, -3, 0, 5, 0, -4, -2, 4, 0, -5, 0, 7, 3, -8, -1, 5, 1, -10, 0, 13, 2, -10, -3, 14, -2, -17, -3, 21, 5, -22, 0, 22, 4, -34, -5, 33, 9, -33, -10, 43, 6, -43, -19, 52, 16, -51, -13, 56, 24, -71, -20, 64, 26, -78, -24, 90, 24, -90, -39, 112, 26, -115, -37
Offset: 0

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Author

Ilya Gutkovskiy, Sep 19 2017

Keywords

Comments

Convolution inverse of A073576.
The difference between the number of partitions of n into an even number of distinct squarefree parts and the number of partitions of n into an odd number of distinct squarefree parts.

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n) option remember; `if`(n=0, 1, add(add(d*
          abs(mobius(d)), d=divisors(j)) *b(n-j), j=1..n)/n)
        end:
    a:= proc(n) option remember; `if`(n=0, 1,
          -add(b(n-i)*a(i), i=0..n-1))
        end:
    seq(a(n), n=0..80);  # Alois P. Heinz, Sep 20 2017
  • Mathematica
    nmax = 75; CoefficientList[Series[Product[1 - MoebiusMu[k]^2 x^k, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 - x^A005117(k)).

A298602 Expansion of (1 - x)*Product_{k>=1} (1 - x^prime(k)).

Original entry on oeis.org

1, -1, -1, 0, 1, 0, 0, 0, 1, 0, -1, -1, 1, 0, 0, 0, 1, -1, 0, -1, 1, 0, 0, -1, 2, 0, -1, -1, 1, -1, 1, -1, 2, 0, 0, -2, 2, -2, 0, 0, 3, -2, 1, -2, 2, -1, 0, -3, 5, -1, 0, -3, 3, -3, 3, -3, 3, -1, 2, -5, 6, -4, 1, -2, 6, -5, 3, -6, 5, -2, 4, -8, 9, -5, 3, -5, 7, -8, 7, -8, 8, -4, 5
Offset: 0

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Author

Ilya Gutkovskiy, Jan 22 2018

Keywords

Comments

The difference between the number of partitions of n into an even number of distinct prime parts (including 1) and the number of partitions of n into an odd number of distinct prime parts (including 1).
Convolution inverse of A034891.

Crossrefs

Cf. A000586, A000607, A034891, A036497, A046675 (partial sums).

Programs

  • Mathematica
    nmax = 82; CoefficientList[Series[(1 - x) Product[(1 - x^Prime[k]), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: (1 - x)*Product_{k>=1} (1 - x^prime(k)).

A350514 Maximal coefficient of Product_{j=1..n} (1 - x^prime(j)).

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 3, 4, 6, 8, 12, 17, 30, 41, 70, 107, 186, 307, 531, 887, 1561, 2701, 4817, 8514, 15030, 26490, 47200, 84622, 151809, 273912, 496807, 900595, 1643185, 2999837, 5498916, 10111429, 18596096, 34306158, 63585519, 118215700
Offset: 0

Views

Author

Alois P. Heinz, Jan 02 2022

Keywords

Crossrefs

Programs

  • Maple
    b:= proc(n) option remember; `if`(n=0, 1,
          expand((1-x^ithprime(n))*b(n-1)))
        end:
    a:= n-> max(coeffs(b(n))):
    seq(a(n), n=0..60);
  • Mathematica
    a[n_] := Times@@(1-x^Prime[Range[n]])//Expand//CoefficientList[#, x]&//Max;
    Table[a[n], {n, 0, 60}] (* Jean-François Alcover, Jun 02 2022 *)
  • PARI
    a(n) = vecmax(Vec(prod(j=1, n, 1-'x^prime(j)))); \\ Michel Marcus, Jan 04 2022
  • Python
    from sympy.abc import x
    from sympy import prime, prod
    def A350514(n): return 1 if n == 0 else max(prod(1-x**prime(i) for i in range(1,n+1)).as_poly().coeffs()) # Chai Wah Wu, Jan 04 2022
    

A298159 G.f.: Product_{k>=1} (1-prime(k)*x^prime(k)).

Original entry on oeis.org

1, 0, -2, -3, 0, 1, 0, 3, 15, 14, -9, -11, -7, 9, -37, -79, 28, 193, -46, -150, -142, -58, -142, 171, 73, 652, 643, 349, -1047, 404, -2743, 873, 3082, 2498, -3039, 411, -2188, 4534, -4571, -9997, -5917, 32879, -14830, -11926, -16333, 7208, -22517, 59885, -27601
Offset: 0

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Author

Seiichi Manyama, Jan 14 2018

Keywords

Crossrefs

Formula

Convolution inverse of A002098.

A184082 Decimal expansion of product_{p=primes} (1-1/2^p).

Original entry on oeis.org

6, 3, 0, 3, 8, 4, 4, 0, 5, 9, 9, 1, 3, 6, 6, 1, 5, 4, 6, 0, 2, 2, 2, 5, 8, 2, 2, 9, 3, 1, 3, 2, 9, 2, 4, 6, 6, 9, 4, 9, 4, 1, 4, 4, 8, 4, 6, 7, 2, 9, 9, 2, 9, 5, 6, 2, 0, 1, 8, 1, 0, 7, 1, 4, 3, 0, 0, 8, 6, 8, 0, 1, 5, 2, 2, 2, 2, 5, 2, 3, 9, 7, 2, 2, 3, 4, 0, 9, 9
Offset: 0

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Author

R. J. Mathar, Jan 09 2011

Keywords

Examples

			(1-1/2^2) *(1-1/2^3) *(1-1/2^5) *(1-1/2^7) *(1-1/2^11) *.... = 0.63038440599136615460222582...
		

Programs

  • Mathematica
    RealDigits[Times@@(1-1/2^Prime[Range[100]]),10,120][[1]] (* Harvey P. Dale, Jun 26 2011 *)

Formula

Equals product_{p in A000040} (1-2^(-p)) = sum_{n>=0} A046675(n)/2^n.

A302234 Expansion of Product_{k>=1} (1 - x^k)/(1 - x^prime(k)).

Original entry on oeis.org

1, -1, 0, 0, -1, 1, -1, 1, -1, 0, 1, 0, 0, 1, 0, -1, 1, 0, 0, 0, 0, -1, 1, -1, 1, -2, 1, -1, 0, 1, -1, 1, -2, 2, -1, -1, 2, -1, -1, 2, -2, 2, -1, 1, 0, -1, 1, 0, 1, -2, 2, 0, 0, 2, -1, 0, 0, 1, 0, 0, 1, -2, 0, -1, 0, 0, -2, 2, -3, 0, 2, -2, 1, -1, 1, -2, 1, -1, -1, 1
Offset: 0

Views

Author

Ilya Gutkovskiy, Apr 03 2018

Keywords

Comments

The difference between the number of partitions of n into an even number of distinct nonprime parts and the number of partitions of n into an odd number of distinct nonprime parts.
Convolution of the sequences A000607 and A010815.

Crossrefs

Programs

  • Mathematica
    nmax = 80; CoefficientList[Series[Product[(1 - x^k)/(1 - x^Prime[k]), {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 80; CoefficientList[Series[Product[(1 - Boole[!PrimeQ[k]] x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} (1 - x^A018252(k)).

A328556 Expansion of Product_{p prime, k>=1} (1 - x^(p^k)).

Original entry on oeis.org

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

Views

Author

Ilya Gutkovskiy, Nov 01 2019

Keywords

Comments

Convolution inverse of A023894.
The difference between the number of partitions of n into an even number of distinct prime power parts and the number of partitions of n into an odd number of distinct prime power parts (1 excluded).
Conjecture: the last zero (38th) occurs at n = 340.

Crossrefs

Programs

  • Maple
    N:= 100: # for a(0)..a(N)
    R:= 1:
    p:= 1:
    do
      p:= nextprime(p);
      if p > N then break fi;
      for k from 1 to floor(log[p](N)) do
        R:= series(R*(1-x^(p^k)),x,N+1)
      od;
    od:
    seq(coeff(R,x,j),j=0..N); # Robert Israel, Nov 03 2019
  • Mathematica
    nmax = 90; CoefficientList[Series[Product[(1 - Boole[PrimePowerQ[k]] x^k), {k, 1, nmax}], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, -Sum[Sum[Boole[PrimePowerQ[d]] d, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 90}]

Formula

G.f.: Product_{k>=1} (1 - x^A246655(k)).

A338826 G.f.: (1/(1 + x)) * Product_{k>=1} 1/(1 + x^prime(k)).

Original entry on oeis.org

1, -1, 0, -1, 2, -2, 2, -3, 4, -4, 5, -7, 8, -9, 11, -13, 15, -18, 21, -24, 28, -32, 37, -43, 49, -55, 63, -72, 81, -92, 104, -117, 131, -147, 166, -185, 206, -231, 257, -285, 317, -353, 391, -432, 478, -528, 583, -643, 708, -778, 855, -940, 1031, -1130, 1238, -1354
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 02 2020

Keywords

Comments

The difference between the number of partitions of n into an even number of prime parts (including 1) and the number of partitions of n into an odd number of prime parts (including 1).
Convolution inverse of A036497.

Crossrefs

Programs

  • Mathematica
    nmax = 55; CoefficientList[Series[(1/(1 + x)) Product[1/(1 + x^Prime[k]), {k, 1, nmax}], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[DivisorSum[k, (-1)^(k/#) # &, PrimeQ[#] || # == 1 &] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 55}]

Formula

a(n) = Sum_{k=0..n} (-1)^(n-k) * A048165(k).
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