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.

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A339721 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^6.

Original entry on oeis.org

1, -6, -6, 15, -6, 30, -6, -26, 15, 30, -6, -60, -6, 30, 30, 51, -6, -60, -6, -60, 30, 30, -6, 96, 15, 30, -26, -60, -6, -114, -6, -102, 30, 30, 30, 96, -6, 30, 30, 96, -6, -114, -6, -60, -60, 30, -6, -210, 15, -60, 30, -60, -6, 96, 30, 96, 30, 30, -6, 156, -6, 30, -60, 172, 30
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 14 2020

Keywords

Crossrefs

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A339338(n/d) * a(d).
a(p^k) = A022601(k) for prime p.

A339722 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^7.

Original entry on oeis.org

1, -7, -7, 21, -7, 42, -7, -42, 21, 42, -7, -105, -7, 42, 42, 84, -7, -105, -7, -105, 42, 42, -7, 189, 21, 42, -42, -105, -7, -203, -7, -175, 42, 42, 42, 217, -7, 42, 42, 189, -7, -203, -7, -105, -105, 42, -7, -399, 21, -105, 42, -105, -7, 189, 42, 189, 42, 42, -7, 385
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 14 2020

Keywords

Crossrefs

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A339339(n/d) * a(d).
a(p^k) = A022602(k) for prime p.

A320835 a(n) = Sum (-1)^k where the sum is over all multiset partitions of a multiset whose multiplicities are the prime indices of n and k is the number of parts, or factorizations of A181821(n).

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Oct 21 2018

Keywords

Comments

This multiset (row n of A305936) is generally not the same as the multiset of prime indices of n. For example, the prime indices of 12 are {1,1,2}, while a multiset whose multiplicities are {1,1,2} is {1,1,2,3}.

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n>k, 0, -1)+`if`(isprime(n), 0,
          -add(`if`(d>k, 0, b(n/d, d)), d=divisors(n) minus {1, n}))
        end:
    a:= n-> `if`(n=1, 1, b(((l-> mul(ithprime(i)^l[i], i=1..nops(l)))(
             sort(map(i-> pi(i[1])$i[2], ifactors(n)[2]), `>`)))$2)):
    seq(a(n), n=1..100);  # Alois P. Heinz, Oct 23 2018
  • Mathematica
    nrmptn[n_]:=Join@@MapIndexed[Table[#2[[1]],{#1}]&,If[n==1,{},Flatten[Cases[FactorInteger[n]//Reverse,{p_,k_}:>Table[PrimePi[p],{k}]]]]];
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    Table[Sum[(-1)^(Length[m]-1),{m,mps[nrmptn[n]]}],{n,30}]

Formula

a(n) = A316441(A181821(n)).

Extensions

More terms from Alois P. Heinz, Oct 21 2018

A320836 a(n) = Sum (-1)^k where the sum is over all strict multiset partitions of a multiset whose multiplicities are the prime indices of n and k is the number of parts, or strict factorizations of A181821(n).

Original entry on oeis.org

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

Views

Author

Gus Wiseman, Oct 21 2018

Keywords

Comments

This multiset (row n of A305936) is generally not the same as the multiset of prime indices of n. For example, the prime indices of 12 are {1,1,2}, while a multiset whose multiplicities are {1,1,2} is {1,1,2,3}.

Crossrefs

Programs

  • Maple
    with(numtheory):
    b:= proc(n, k) option remember; `if`(n>k, 0, -1)+`if`(isprime(n), 0,
          -add(`if`(d>k, 0, b(n/d, d-1)), d=divisors(n) minus {1, n}))
        end:
    a:= n-> `if`(n=1, 1, b(((l-> mul(ithprime(i)^l[i], i=1..nops(l)))(
             sort(map(i-> pi(i[1])$i[2], ifactors(n)[2]), `>`)))$2)):
    seq(a(n), n=1..100);  # Alois P. Heinz, Oct 23 2018
  • Mathematica
    nrmptn[n_]:=Join@@MapIndexed[Table[#2[[1]],{#1}]&,If[n==1,{},Flatten[Cases[FactorInteger[n]//Reverse,{p_,k_}:>Table[PrimePi[p],{k}]]]]];
    sps[{}]:={{}};sps[set:{i_,_}]:=Join@@Function[s,Prepend[#,s]&/@sps[Complement[set,s]]]/@Cases[Subsets[set],{i,_}];
    mps[set_]:=Union[Sort[Sort/@(#/.x_Integer:>set[[x]])]&/@sps[Range[Length[set]]]];
    Table[Sum[(-1)^Length[m],{m,Select[mps[nrmptn[n]],UnsameQ@@#&]}],{n,30}]

Formula

a(n) = A114592(A181821(n)).

Extensions

More terms from Alois P. Heinz, Oct 21 2018

A328731 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^k.

Original entry on oeis.org

1, -2, -3, -1, -5, 0, -7, -4, -3, 0, -11, 3, -13, 0, 0, 3, -17, 6, -19, 5, 0, 0, -23, 18, -10, 0, -10, 7, -29, 30, -31, -2, 0, 0, 0, 24, -37, 0, 0, 30, -41, 42, -43, 11, 15, 0, -47, 27, -21, 20, 0, 13, -53, 38, 0, 42, 0, 0, -59, 60, -61, 0, 21, 17, 0, 66, -67, 17, 0, 70
Offset: 1

Views

Author

Ilya Gutkovskiy, Oct 26 2019

Keywords

Comments

Dirichlet inverse of A050368.

Crossrefs

Cf. A006881 (positions of 0's), A050368, A316441, A328730.

Formula

a(1) = 1; a(n) = -Sum_{d|n, dA050368(n/d) * a(d).

A344369 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(1-s)).

Original entry on oeis.org

1, -2, -3, 0, -5, 0, -7, -8, 0, 0, -11, 0, -13, 0, 0, 16, -17, 0, -19, 0, 0, 0, -23, 24, 0, 0, -27, 0, -29, 30, -31, -32, 0, 0, 0, 36, -37, 0, 0, 40, -41, 42, -43, 0, 0, 0, -47, 0, 0, 0, 0, 0, -53, 54, 0, 56, 0, 0, -59, 60, -61, 0, 0, 64, 0, 66, -67, 0, 0, 70
Offset: 1

Views

Author

Ilya Gutkovskiy, May 16 2021

Keywords

Crossrefs

Programs

  • Mathematica
    facs[n_] := If[n <= 1, {{}}, Join @@ Table[Map[Prepend[#, d] &, Select[facs[n/d], Min @@ # >= d &]], {d, Rest[Divisors[n]]}]]; A316441[n_] := Sum[(-1)^Length[f], {f, facs[n]}]; Table[n A316441[n], {n, 70}]

Formula

a(n) = n * A316441(n).

A328877 Dirichlet g.f.: Product_{k>=2} (1 + k^(-s))^(k - 1).

Original entry on oeis.org

1, 1, 2, 3, 4, 7, 6, 10, 9, 13, 10, 22, 12, 19, 22, 25, 16, 36, 18, 40, 32, 31, 22, 69, 30, 37, 42, 58, 28, 89, 30, 70, 52, 49, 58, 121, 36, 55, 62, 125, 40, 129, 42, 94, 108, 67, 46, 203, 63, 115, 82, 112, 52, 174, 94, 181, 92, 85, 58, 319, 60, 91, 156, 182
Offset: 1

Views

Author

Ilya Gutkovskiy, Oct 29 2019

Keywords

Comments

Number of ways to factor n into distinct factors with 1 kind of 2, 2 kinds of 3, ..., k-1 kinds of k.
Dirichlet convolution of A050368 with A316441.

Crossrefs

Programs

  • PARI
    seq(n)={my(v=vector(n, k, k==1)); for(k=2, n, my(m=logint(n, k), p=(1 + x + O(x*x^m))^(k-1), w=vector(n)); for(i=0, m, w[k^i]=polcoef(p, i)); v=dirmul(v, w)); v} \\ Andrew Howroyd, Oct 29 2019

Formula

a(n) = Sum_{d|n} A050368(n/d) * A316441(d).

A339734 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^8.

Original entry on oeis.org

1, -8, -8, 28, -8, 56, -8, -64, 28, 56, -8, -168, -8, 56, 56, 134, -8, -168, -8, -168, 56, 56, -8, 344, 28, 56, -64, -168, -8, -328, -8, -288, 56, 56, 56, 428, -8, 56, 56, 344, -8, -328, -8, -168, -168, 56, -8, -728, 28, -168, 56, -168, -8, 344, 56, 344, 56, 56, -8, 792
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 14 2020

Keywords

Crossrefs

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A339340(n/d) * a(d).
a(p^k) = A007259(k) for prime p.

A339735 Dirichlet g.f.: Product_{k>=2} 1 / (1 + k^(-s))^9.

Original entry on oeis.org

1, -9, -9, 36, -9, 72, -9, -93, 36, 72, -9, -252, -9, 72, 72, 207, -9, -252, -9, -252, 72, 72, -9, 585, 36, 72, -93, -252, -9, -495, -9, -459, 72, 72, 72, 765, -9, 72, 72, 585, -9, -495, -9, -252, -252, 72, -9, -1278, 36, -252, 72, -252, -9, 585, 72, 585, 72, 72, -9, 1449
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 14 2020

Keywords

Crossrefs

Formula

a(1) = 1; a(n) = -Sum_{d|n, d < n} A339341(n/d) * a(d).
a(p^k) = A022604(k) for prime p.

A351023 Dirichlet g.f.: Product_{k>=2} 1 / (1 + 2 * k^(-s)).

Original entry on oeis.org

1, -2, -2, 2, -2, 2, -2, -6, 2, 2, -2, -2, -2, 2, 2, 14, -2, -2, -2, -2, 2, 2, -2, 10, 2, 2, -6, -2, -2, 2, -2, -26, 2, 2, 2, 6, -2, 2, 2, 10, -2, 2, -2, -2, -2, 2, -2, -18, 2, -2, 2, -2, -2, 10, 2, 10, 2, 2, -2, 2, -2, 2, -2, 50, 2, 2, -2, -2, 2, 2, -2, -14, -2, 2, -2
Offset: 1

Views

Author

Ilya Gutkovskiy, Jan 29 2022

Keywords

Crossrefs

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