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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A258997 A(n,k) = pi-based antiderivative of n^k; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 4, 2, 0, 0, 0, 12, 12, 4, 0, 0, 0, 32, 54, 32, 3, 0, 0, 0, 80, 216, 192, 30, 7, 0, 0, 0, 192, 810, 1024, 225, 84, 4, 0, 0, 0, 448, 2916, 5120, 1500, 756, 56, 12, 0, 0, 0, 1024, 10206, 24576, 9375, 6048, 588, 192, 12, 0
Offset: 0

Views

Author

Alois P. Heinz, Jun 27 2015

Keywords

Examples

			Square array A(n,k) begins:
  0, 0,  0,   0,    0,     0,      0,       0, ...
  0, 0,  0,   0,    0,     0,      0,       0, ...
  0, 1,  4,  12,   32,    80,    192,     448, ...
  0, 2, 12,  54,  216,   810,   2916,   10206, ...
  0, 4, 32, 192, 1024,  5120,  24576,  114688, ...
  0, 3, 30, 225, 1500,  9375,  56250,  328125, ...
  0, 7, 84, 756, 6048, 45360, 326592, 2286144, ...
  0, 4, 56, 588, 5488, 48020, 403368, 3294172, ...
		

Crossrefs

Rows n=0+1,2,3,4,8 give: A000004, A001787, A212697, A018215, A230539.
Columns k=0,1 give: A000004, A258851.
Main diagonal gives A258846.
Cf. A000720.

Programs

  • Maple
    with(numtheory):
    d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
    A:= (n, k)-> `if`(k=0, 0, k*n^(k-1)*d(n)):
    seq(seq(A(n, h-n), n=0..h), h=0..14);

Formula

A(n,k) = A258851(n^k) = k * n^(k-1) * A258851(n).

A328769 The second primorial based variant of arithmetic derivative: a(p) = A034386(p) for p prime, a(u*v) = a(u)*v + u*a(v), with a(0) = a(1) = 0.

Original entry on oeis.org

0, 0, 2, 6, 8, 30, 18, 210, 24, 36, 70, 2310, 48, 30030, 434, 120, 64, 510510, 90, 9699690, 160, 672, 4642, 223092870, 120, 300, 60086, 162, 896, 6469693230, 270, 200560490130, 160, 6996, 1021054, 1260, 216, 7420738134810, 19399418, 90168, 360, 304250263527210, 1386, 13082761331670030, 9328, 450, 446185786, 614889782588491410, 288, 2940, 650, 1531632
Offset: 0

Views

Author

Antti Karttunen, Oct 28 2019

Keywords

Crossrefs

Programs

  • PARI
    A034386(n) = factorback(primes(primepi(n)));
    A328769(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A034386(f[i,1])/f[i, 1]));
    
  • PARI
    A002110(n) = prod(i=1,n,prime(i));
    A328769(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]*A002110(primepi(f[i,1]))/f[i, 1]));

Formula

a(n) = n * Sum e_j * (p_j)#/p_j for n = Product p_j^e_j with (p_j)# = A034386(p_j).
A276150(a(n)) = A328772(n).

A259153 Triangle T(n,k) in which n-th row lists in increasing order the values v whose pi-based arithmetic derivative equals n; n>=0, 1<=k<=A259154(n).

Original entry on oeis.org

0, 1, 2, 3, 5, 4, 7, 11, 13, 6, 17, 19, 23, 29, 10, 31, 8, 9, 37, 41, 43, 14, 47, 53, 59, 61, 15, 67, 12, 71, 22, 73, 79, 83, 89, 26, 97, 21, 101, 103, 107, 109, 25, 113, 34, 127, 16, 20, 131, 18, 137, 139, 38, 149, 151, 33, 157, 163, 167, 173, 35, 46, 179
Offset: 0

Views

Author

Alois P. Heinz, Jun 19 2015

Keywords

Examples

			Triangle T(n,k) begins:
   0,  1;
   2;
   3;
   5;
   4,  7;
  11;
  13;
   6, 17;
  19;
  23;
  29;
  10, 31;
   8,  9, 37;
		

Crossrefs

Column k=1 gives A258861.
Last elements of rows give A008578(n+1).
Row lengths give A259154.
Row sums give A259155.

Formula

A258851(T(n,k)) = n.
T(n,1) = A258861(n).
T(n,A259154(n)) = A008578(n+1).
T(n,A259154(n)) = A000040(n) for n>0.

A353379 Primepi-based variant of the arithmetic derivative applied to the prime shadow of n.

Original entry on oeis.org

0, 1, 1, 2, 1, 4, 1, 3, 2, 4, 1, 7, 1, 4, 4, 4, 1, 7, 1, 7, 4, 4, 1, 11, 2, 4, 3, 7, 1, 12, 1, 5, 4, 4, 4, 12, 1, 4, 4, 11, 1, 12, 1, 7, 7, 4, 1, 15, 2, 7, 4, 7, 1, 11, 4, 11, 4, 4, 1, 20, 1, 4, 7, 6, 4, 12, 1, 7, 4, 12, 1, 19, 1, 4, 7, 7, 4, 12, 1, 15, 4, 4, 1, 20, 4, 4, 4, 11, 1, 20, 4, 7, 4, 4, 4, 21, 1, 7, 7
Offset: 1

Views

Author

Antti Karttunen, Apr 28 2022

Keywords

Crossrefs

Cf. also A351942.

Programs

  • Maple
    a:= n-> (m-> m*add(i[2]*numtheory[pi](i[1])/i[1], i=ifactors(m)[2]))
            (mul(ithprime(i[2]), i=ifactors(n)[2])):
    seq(a(n), n=1..120);  # Alois P. Heinz, Apr 28 2022
  • Mathematica
    a[n_] := If[n == 1, 0, #*Sum[i[[2]]*PrimePi[i[[1]]]/i[[1]], {i, FactorInteger[#]}]]&[Product[Prime[i[[2]]], {i, FactorInteger[n]}]];
    Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Jan 29 2025, after Alois P. Heinz *)
  • PARI
    A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
    A258851(n) = (n*sum(i=1, #n=factor(n)~, n[2, i]*primepi(n[1, i])/n[1, i])); \\ From A258851
    A353379(n) = A258851(A181819(n));

Formula

a(n) = A258851(A181819(n)).

A097240 a(n) = (n+1)*prime(n) + n*prime(n+1).

Original entry on oeis.org

7, 19, 41, 79, 131, 193, 269, 355, 491, 629, 779, 973, 1133, 1303, 1547, 1845, 2099, 2365, 2689, 2951, 3265, 3643, 4039, 4553, 5047, 5405, 5773, 6155, 6547, 7313, 8125, 8707, 9245, 9931, 10649, 11239, 11997, 12703, 13427, 14253, 14939, 15805, 16703
Offset: 1

Views

Author

Reinhard Zumkeller, Aug 02 2004

Keywords

Comments

Of the first 10000 terms, 1540 are primes. - Antti Karttunen, Jul 30 2022

Crossrefs

Cf. A000040, A006094, A097241 (primes in this sequence), A258851.
Column 3 of A356155.

Programs

Formula

a(n) = A258851(A006094(n)). - Antti Karttunen, Jul 30 2022

A258852 Second pi-based arithmetic derivative of n.

Original entry on oeis.org

0, 0, 0, 1, 4, 2, 4, 4, 20, 20, 5, 3, 32, 7, 19, 8, 80, 4, 37, 12, 80, 25, 26, 12, 76, 53, 30, 135, 64, 11, 16, 5, 208, 12, 11, 13, 188, 20, 41, 64, 188, 6, 21, 15, 192, 88, 13, 19, 448, 116, 86, 58, 108, 32, 351, 49, 156, 53, 56, 7, 260, 33, 16, 332, 704, 73
Offset: 0

Views

Author

Alois P. Heinz, Jun 12 2015

Keywords

Crossrefs

Column k=2 of A258850.

Programs

  • Maple
    with(numtheory):
    d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
    A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end:
    a:= n-> A(n, 2):
    seq(a(n), n=0..100);

Formula

a(n) = A258851^2(n).
a(A258862(n)) = n.

A258853 Third pi-based arithmetic derivative of n.

Original entry on oeis.org

0, 0, 0, 0, 4, 1, 4, 4, 32, 32, 3, 2, 80, 4, 8, 12, 208, 4, 12, 20, 208, 30, 25, 20, 108, 16, 53, 351, 192, 5, 32, 3, 512, 20, 5, 6, 248, 32, 13, 192, 248, 7, 26, 19, 704, 172, 6, 8, 1600, 156, 71, 49, 324, 80, 864, 56, 332, 16, 116, 4, 536, 37, 32, 424, 2432
Offset: 0

Views

Author

Alois P. Heinz, Jun 12 2015

Keywords

Crossrefs

Column k=3 of A258850.

Programs

  • Maple
    with(numtheory):
    d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
    A:= proc(n, k) option remember; `if`(k=0, n, d(A(n, k-1))) end:
    a:= n-> A(n, 3):
    seq(a(n), n=0..100);

Formula

a(n) = A258851^3(n).
a(A258995(n)) = n.

A259154 Number of values v whose pi-based arithmetic derivative equals n.

Original entry on oeis.org

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

Views

Author

Alois P. Heinz, Jun 19 2015

Keywords

Comments

a(n) > 0 for all n >= 0.

Crossrefs

Row lengths of A259153.

Formula

a(n) = |{ v >= 0 : A258851(v) = n }|.

A120272 Numerator of Sum_{k=1..n} k/prime(k).

Original entry on oeis.org

0, 1, 7, 53, 491, 6451, 97723, 1871501, 39642599, 999076987, 31204161323, 1038495626543, 40831064063651, 1770543222362221, 80392862250956443, 3974705945770003271, 220497651647226035923, 13563377141298566879867, 861975691921988407175147, 59980850604601955729416979
Offset: 0

Views

Author

Alexander Adamchuk, Jul 01 2006

Keywords

Crossrefs

Denominators are in A002110.

Programs

  • Magma
    [0] cat [Numerator((&+[k/NthPrime(k): k in [1..n]])): n in [1..20]]; // G. C. Greubel, Aug 23 2018
  • Mathematica
    Numerator[Table[Sum[i/Prime[i],{i,1,n}],{n,1,20}]]
    Numerator[Accumulate[Table[n/Prime[n],{n,20}]]] (* Harvey P. Dale, Jan 21 2013 *)
  • PARI
    for(n=0,20, print1(if(n==0, 0, numerator(sum(k=1,n, k/prime(k)))), ", ")) \\ G. C. Greubel, Aug 23 2018
    

Formula

a(n) = A258851(A002110(n)). - Alois P. Heinz, Jun 26 2015

Extensions

a(0)=0 prepended by Alois P. Heinz, Jun 26 2015

A258845 The pi-based arithmetic derivative of n!.

Original entry on oeis.org

0, 0, 1, 7, 52, 332, 2832, 22704, 242112, 2662848, 30620160, 354965760, 5057925120, 68627036160, 1054183818240, 17469144806400, 321351896678400, 5609441772748800, 112707637036646400, 2192664093342105600, 47745925079924736000, 1065919878891012096000
Offset: 0

Views

Author

Alois P. Heinz, Jun 12 2015

Keywords

Crossrefs

Programs

  • Maple
    with(numtheory):
    d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
    a:= proc(n) option remember;
          `if`(n<2, 0, a(n-1)*n+(n-1)!*d(n))
        end:
    seq(a(n), n=0..25);
  • Mathematica
    d[n_] := n*Sum[i[[2]]*PrimePi[i[[1]]]/i[[1]], {i, FactorInteger[n]}];
    a[n_] := a[n] = If[n < 2, 0, a[n-1]*n + (n-1)!*d[n]];
    Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Mar 24 2017, translated from Maple *)

Formula

a(n) = A258851(n!) = A258851(A000142(n)).
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