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 49 results. Next

A258861 The pi-based antiderivative of n: the least m such that A258851(m) equals n.

Original entry on oeis.org

0, 2, 3, 5, 4, 11, 13, 6, 19, 23, 29, 10, 8, 41, 43, 14, 53, 59, 61, 15, 12, 22, 79, 83, 89, 26, 21, 103, 107, 109, 25, 34, 16, 18, 139, 38, 151, 33, 163, 167, 173, 35, 181, 191, 28, 197, 199, 211, 223, 58, 229, 233, 24, 30, 27, 51, 49, 269, 55, 277, 281, 74
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() local t, a; t, a:= -1, proc() -1 end;
          proc(n) local h;
            while a(n) = -1 do
              t:= t+1; h:= d(t);
              if a(h) = -1 then a(h):= t fi
            od; a(n)
          end
        end():
    seq(a(n), n=0..100);
  • Mathematica
    A258851[n_] := If[n == 0, 0, n*Total[Last[#]*PrimePi[First[#]]/First[#]& /@ FactorInteger[n]]];
    a[n_] := For[m = 0, True, m++, If[A258851[m] == n, Return[m]]];
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Sep 10 2023 *)

Formula

a(n) = min { m >= 0 : A258851(m) = n }.
A258851(a(n)) = n.
a(n) <= A000040(n) for n>0.

A258862 Second pi-based antiderivative of n: the least m such that A258851^2(m) equals n.

Original entry on oeis.org

0, 3, 5, 11, 4, 10, 41, 13, 15, 83, 109, 29, 19, 35, 191, 43, 30, 277, 74, 14, 8, 42, 77, 431, 461, 21, 22, 563, 66, 599, 26, 78, 12, 61, 141, 163, 877, 18, 214, 218, 226, 38, 114, 201, 105, 1201, 215, 1297, 302, 55, 1447, 1471, 89, 25, 103, 170, 58, 291, 51
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() local t, a; t, a:= -1, proc() -1 end;
          proc(n) local h;
            while a(n) = -1 do
              t:= t+1; h:= d(d(t));
              if a(h) = -1 then a(h):= t fi
            od; a(n)
          end
        end():
    seq(a(n), n=0..100);
  • Mathematica
    d[n_] := 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]]];
    a[n_] := A[n, 2];
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, May 17 2024 *)

Formula

a(n) = min { m >= 0 : A258851^2(m) = n }.
A258851^2(a(n)) = A258852(a(n)) = n.
a(n) <= A000040^2(n) for n>0.
a(n) <= A258861^2(n); a(21) = 42 < A258861^2(21) = A258861(22) = 79; A258851^2(42) = A258851^2(79) = 21.

A258995 Third pi-based antiderivative of n: the least m such that A258851^3(m) equals n.

Original entry on oeis.org

0, 5, 11, 10, 4, 29, 35, 41, 14, 431, 599, 78, 15, 38, 201, 191, 25, 382, 186, 43, 19, 65, 94, 3001, 535, 22, 42, 633, 317, 4397, 21, 141, 8, 74, 574, 214, 1286, 61, 253, 247, 1417, 163, 115, 217, 66, 546, 138, 10631, 1997, 51, 12097, 12301, 362, 26, 563, 1013
Offset: 0

Views

Author

Alois P. Heinz, Jun 16 2015

Keywords

Crossrefs

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:= -1, proc() -1 end;
          proc(n) local h;
            while a(n) = -1 do
              t:= t+1; h:= d(d(d(t)));
              if a(h) = -1 then a(h):= t fi
            od; a(n)
          end
        end():
    seq(a(n), n=0..100);
  • Mathematica
    d[n_] := 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]]];
    a[n_] := A[n, 3];
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, May 17 2024 *)

Formula

a(n) = min { m >= 0 : A258851^3(m) = n }.
A258851^3(a(n)) = A258853(a(n)) = n.
a(n) <= A000040^3(n) for n>0.
a(n) <= A258861^3(n).

A278510 a(n) = A258851(n) - A056239(n).

Original entry on oeis.org

0, 0, 0, 2, 0, 4, 0, 9, 8, 7, 0, 16, 0, 10, 14, 28, 0, 28, 0, 27, 20, 15, 0, 47, 24, 18, 48, 38, 0, 47, 0, 75, 30, 23, 34, 78, 0, 26, 36, 78, 0, 66, 0, 57, 80, 31, 0, 122, 48, 78, 46, 68, 0, 128, 50, 109, 52, 38, 0, 129, 0, 41, 112, 186, 60, 99, 0, 87, 62, 109, 0, 197, 0, 48, 132, 98, 70, 118, 0, 201, 208, 53, 0, 180, 76, 56, 76, 164, 0, 211, 84, 117, 82, 61
Offset: 1

Views

Author

Antti Karttunen, Dec 11 2016

Keywords

Crossrefs

Cf. A008578 (positions of zeros).

Formula

a(n) = A258851(n) - A056239(n).

A353575 Primepi based arithmetic derivative applied to the prime shadow of the primorial base exp-function: a(n) = A258851(A181819(A276086(n))).

Original entry on oeis.org

0, 1, 1, 4, 2, 7, 1, 4, 4, 12, 7, 20, 2, 7, 7, 20, 12, 33, 3, 11, 11, 32, 19, 53, 4, 15, 15, 44, 26, 73, 1, 4, 4, 12, 7, 20, 4, 12, 12, 32, 20, 52, 7, 20, 20, 52, 33, 84, 11, 32, 32, 84, 53, 136, 15, 44, 44, 116, 73, 188, 2, 7, 7, 20, 12, 33, 7, 20, 20, 52, 33, 84, 12, 33, 33, 84, 54, 135, 19, 53, 53, 136, 87, 219
Offset: 0

Views

Author

Antti Karttunen, Apr 29 2022

Keywords

Crossrefs

Programs

Formula

a(n) = A353379(A276086(n)) = A258851(A328835(n)).

A354871 a(n) = gcd(A056239(n), A258851(n)).

Original entry on oeis.org

0, 1, 2, 2, 3, 1, 4, 3, 4, 1, 5, 4, 6, 5, 1, 4, 7, 1, 8, 1, 2, 3, 9, 1, 6, 1, 6, 2, 10, 1, 11, 5, 1, 1, 1, 6, 12, 1, 4, 6, 13, 1, 14, 1, 1, 1, 15, 2, 8, 1, 1, 4, 16, 1, 2, 1, 2, 1, 17, 1, 18, 1, 8, 6, 3, 1, 19, 3, 1, 1, 20, 1, 21, 1, 4, 2, 1, 1, 22, 1, 8, 1, 23, 4, 2, 1, 4, 4, 24, 1, 2, 1, 1, 1, 1, 1, 25, 1, 3, 4
Offset: 1

Views

Author

Antti Karttunen, Jun 11 2022

Keywords

Crossrefs

Programs

  • PARI
    A056239(n) = { my(f); if(1==n, 0, f=factor(n); sum(i=1, #f~, f[i, 2] * primepi(f[i, 1]))); }
    A258851(n) = (n*sum(i=1, #n=factor(n)~, n[2, i]*primepi(n[1, i])/n[1, i])); \\ From A258851
    A354871(n) = gcd(A056239(n), A258851(n));

Formula

a(n) = gcd(A056239(n), A258851(n)).
a(n) = gcd(A056239(n), A278510(n)) = gcd(A258851(n), A278510(n)).
For n > 1, a(n) = A056239(n) / A354872(n) = A258851(n) / A354873(n).

A356155 The pi-based arithmetic derivative applied to prime shift array: Square array A(n,k) = A258851(A246278(n,k)), read by falling antidiagonals.

Original entry on oeis.org

1, 4, 2, 7, 12, 3, 12, 19, 30, 4, 11, 54, 41, 56, 5, 20, 26, 225, 79, 110, 6, 15, 87, 58, 588, 131, 156, 7, 32, 37, 310, 94, 1815, 193, 238, 8, 33, 216, 69, 861, 162, 3042, 269, 304, 9, 32, 140, 1500, 117, 2156, 218, 6069, 355, 414, 10, 21, 120, 427, 5488, 183, 3835, 314, 8664, 491, 580, 11, 52, 44, 455, 1254, 26620, 255, 6834, 422, 14283, 629, 682, 12
Offset: 1

Views

Author

Antti Karttunen, Jul 29 2022

Keywords

Comments

Each column is strictly monotonic.

Examples

			The top left corner of the array:
   k =  1    2    3      4    5      6    7       8      9     10   11       12
  2k =  2    4    6      8   10     12   14      16     18     20   22       24
-----+--------------------------------------------------------------------------
n= 1 |  1,   4,   7,    12,  11,    20,  15,     32,    33,    32,  21,      52,
   2 |  2,  12,  19,    54,  26,    87,  37,    216,   140,   120,  44,     351,
   3 |  3,  30,  41,   225,  58,   310,  69,   1500,   427,   455,  86,    2075,
   4 |  4,  56,  79,   588,  94,   861, 117,   5488,  1254,  1022, 132,    8183,
   5 |  5, 110, 131,  1815, 162,  2156, 183,  26620,  2561,  2717, 214,   31581,
   6 |  6, 156, 193,  3042, 218,  3835, 255,  52728,  4828,  4316, 304,   67093,
   7 |  7, 238, 269,  6069, 314,  6834, 373, 137564,  7695,  8075, 404,  154615,
   8 |  8, 304, 355,  8664, 422, 10241, 457, 219488, 12098, 12426, 524,  261003,
   9 |  9, 414, 491, 14283, 532, 17296, 609, 438012, 20909, 18653, 668,  535877,
  10 | 10, 580, 629, 25230, 718, 27231, 787, 975560, 29388, 31552, 836, 1050409,
		

Crossrefs

Cf. A000027 (column 1), A097240 (column 3), A246278, A258851.
Cf. also A344027.

Programs

  • PARI
    up_to = 78;
    A246278sq(row,col) = if(1==row,2*col, my(f = factor(2*col)); for(i=1, #f~, f[i,1] = prime(primepi(f[i,1])+(row-1))); factorback(f));
    A258851(n) = (n*sum(i=1, #n=factor(n)~, n[2, i]*primepi(n[1, i])/n[1, i])); \\ From A258851
    A356155sq(row,col) = A258851(A246278sq(row,col));
    A356155list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A356155sq(col,(a-(col-1))))); (v); };
    v356155 = A356155list(up_to);
    A356155(n) = v356155[n];

A354872 a(n) = A056239(n) / gcd(A056239(n), A258851(n)).

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 1, 4, 1, 1, 1, 1, 5, 1, 1, 5, 1, 5, 3, 2, 1, 5, 1, 7, 1, 3, 1, 6, 1, 1, 7, 8, 7, 1, 1, 9, 2, 1, 1, 7, 1, 7, 7, 10, 1, 3, 1, 7, 9, 2, 1, 7, 4, 7, 5, 11, 1, 7, 1, 12, 1, 1, 3, 8, 1, 3, 11, 8, 1, 7, 1, 13, 2, 5, 9, 9, 1, 7, 1, 14, 1, 2, 5, 15, 3, 2, 1, 8, 5, 11, 13, 16, 11, 7, 1, 9, 3, 2, 1, 10
Offset: 2

Views

Author

Antti Karttunen, Jun 11 2022

Keywords

Comments

Numerator of fraction A056239(n) / A258851(n).

Crossrefs

Cf. A056239, A258851, A278510, A354871, A354873 (denominators).

Programs

Formula

a(n) = A056239(n) / A354871(n) = A056239(n) / gcd(A056239(n), A258851(n)).

A354873 a(n) = A258851(n) / gcd(A056239(n), A258851(n)).

Original entry on oeis.org

1, 1, 2, 1, 7, 1, 4, 3, 11, 1, 5, 1, 3, 19, 8, 1, 33, 1, 32, 13, 7, 1, 52, 5, 25, 9, 22, 1, 53, 1, 16, 37, 31, 41, 14, 1, 35, 11, 14, 1, 73, 1, 64, 87, 41, 1, 64, 7, 85, 55, 19, 1, 135, 29, 116, 31, 49, 1, 136, 1, 53, 15, 32, 23, 107, 1, 32, 73, 117, 1, 204, 1, 61, 35, 54, 79, 127, 1, 208, 27, 67, 1, 47, 43, 71, 22
Offset: 2

Views

Author

Antti Karttunen, Jun 11 2022

Keywords

Comments

Denominator of fraction A056239(n) / A258851(n).

Crossrefs

Cf. A056239, A258851, A278510, A354871, A354872 (numerators).

Programs

Formula

a(n) = A258851(n) / A354871(n) = A258851(n) / gcd(A056239(n), A258851(n)).

A258863 First differences of the pi-based arithmetic derivative sequence A258851.

Original entry on oeis.org

0, 1, 1, 2, -1, 4, -3, 8, 0, -1, -6, 15, -14, 9, 4, 13, -25, 26, -25, 24, -6, -5, -12, 43, -22, -5, 29, -10, -34, 43, -42, 69, -43, -6, 10, 43, -72, 23, 9, 40, -71, 60, -59, 50, 23, -46, -26, 113, -72, 29, -30, 21, -60, 119, -77, 58, -54, -13, -32, 119, -118
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:= n-> d(n+1)-d(n):
    seq(a(n), n=0..100);

Formula

a(n) = A258851(n+1) - A258851(n).
Showing 1-10 of 49 results. Next