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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A259016 A(n,k) = k-th pi-based antiderivative of n; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

0, 0, 1, 0, 2, 2, 0, 3, 3, 3, 0, 5, 5, 5, 4, 0, 11, 11, 11, 4, 5, 0, 10, 10, 10, 4, 11, 6, 0, 29, 29, 29, 4, 10, 13, 7, 0, 78, 78, 78, 4, 29, 41, 6, 8, 0, 141, 141, 141, 4, 78, 35, 13, 19, 9, 0, 266, 266, 266, 4, 141, 38, 41, 15, 23, 10, 0, 147, 147, 147, 4, 266, 163, 35, 14, 83, 29, 11
Offset: 0

Views

Author

Alois P. Heinz, Jun 16 2015

Keywords

Examples

			A(5,3) = 29 -> 10 -> 11 -> 5.
A(5,4) = 78 -> 127 -> 31 -> 11 -> 5.
Square array A(n,k) begins:
  0,  0,  0,   0,    0,     0,     0,      0,     0,      0, ...
  1,  2,  3,   5,   11,    10,    29,     78,   141,    266, ...
  2,  3,  5,  11,   10,    29,    78,    141,   266,    147, ...
  3,  5, 11,  10,   29,    78,   141,    266,   147,    194, ...
  4,  4,  4,   4,    4,     4,     4,      4,     4,      4, ...
  5, 11, 10,  29,   78,   141,   266,    147,   194,   1181, ...
  6, 13, 41,  35,   38,   163,   138,    253,   346,   1383, ...
  7,  6, 13,  41,   35,    38,   163,    138,   253,    346, ...
  8, 19, 15,  14,   43,   191,   201,    217,  1113,   1239, ...
  9, 23, 83, 431, 3001, 27457, 10626, 112087, 87306, 172810, ...
		

Crossrefs

Columns k=0-3 give: A001477, A258861, A258862, A258995.
Rows n=0,1,4,7,8,9 give: A000004, A258975, A010709, A259168, A259169, A259170.

Programs

  • Maple
    with(numtheory):
    d:= n-> n*add(i[2]*pi(i[1])/i[1], i=ifactors(n)[2]):
    A:= proc() local t, A; t, A:= proc()-1 end, proc()-1 end;
          proc(n, k) local h;
            while A(n, k) = -1 do
              t(k):= t(k)+1; h:= (d@@k)(t(k));
              if A(h, k) = -1 then A(h, k):= t(k) fi
            od; A(n, k)
          end
        end():
    seq(seq(A(n, h-n), n=0..h), h=0..12);
  • Mathematica
    d[n_] := If[n == 0, 0, n*Total[Last[#]*PrimePi[First[#]]/First[#]& /@ FactorInteger[n]]];
    A[n_, k_] := For[m = 0, True, m++, If[Nest[d, m, k] == n, Return[m]]];
    Table[A[n, k-n], {k, 0, 12}, {n, 0, k}] // Flatten (* Jean-François Alcover, Mar 20 2017 *)

Formula

A(n,k) = min { m >= 0 : A258851^k(m) = n }.
A258850(A(n,k),k) = n.
A(n,k) <= A000040^k(n) for n>0.

A258848 The n-th pi-based arithmetic derivative of 2^3.

Original entry on oeis.org

8, 12, 20, 32, 80, 208, 512, 2304, 12288, 81920, 622592, 4931584, 38944768, 278380544, 2122727424, 17483677696, 128412352512, 1348723408896, 14768867966976, 188484960780288, 2416519442792448, 30543291749302272, 375877192068366336, 6101345960934506496
Offset: 0

Views

Author

Alois P. Heinz, Jun 12 2015

Keywords

Crossrefs

Row n=8 of A258850.

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=0, 2^3, d(a(n-1))) end:
    seq(a(n), n=0..23);

Formula

a(n) = A258851^n(2^3).
Showing 1-2 of 2 results.