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 1-5 of 5 results.

A054786 Earliest sequence with a(a(n)) = 6n.

Original entry on oeis.org

0, 2, 6, 4, 18, 7, 12, 30, 9, 48, 11, 60, 36, 14, 78, 16, 90, 19, 24, 102, 21, 120, 23, 132, 108, 26, 150, 28, 162, 31, 42, 174, 33, 192, 35, 204, 72, 38, 222, 40, 234, 43, 180, 246, 45, 264, 47, 276, 54, 50, 294, 52, 306, 55, 288, 318, 57, 336, 59, 348, 66, 62, 366, 64
Offset: 0

Views

Author

Henry Bottomley, Apr 27 2000

Keywords

Links

Crossrefs

Cf. A002516, A002517, A002518, A007379.

Programs

  • Mathematica
    a[0] = 0; a[n_] := a[n] = Switch[ Mod[n, 12], 0 | 6, 6*a[n/6], 1 | 3 | 8 | 10, n+1, 2 | 4 | 9 | 11, 6*n-6, 5, n+2, 7, 6*n-12]; Table[a[n], {n, 0, 63}] (* Jean-François Alcover, Dec 20 2011, after formula *)

Formula

a(12n)=6*a(2n), a(12n+1)=12n+2, a(12n+2)=72n+6, a(12n+3)=12n+4, a(12n+4)=72n+18, a(12n+5)=12n+7, a(12n+6)=6*a(2n+1), a(12n+7)=72n+30, a(12n+8)=12n+9, a(12n+9)=72n+48, a(12n+10)=12n+11, a(12n+11)=72n+60.

Extensions

Typo in formula corrected by Reinhard Zumkeller, Jul 23 2010

A054787 Earliest sequence with a(a(n))=7n.

Original entry on oeis.org

0, 2, 7, 4, 21, 6, 35, 14, 9, 56, 11, 70, 13, 84, 49, 16, 105, 18, 119, 20, 133, 28, 23, 154, 25, 168, 27, 182, 147, 30, 203, 32, 217, 34, 231, 42, 37, 252, 39, 266, 41, 280, 245, 44, 301, 46, 315, 48, 329, 98, 51, 350, 53, 364, 55, 378, 63, 58, 399, 60, 413, 62, 427, 392
Offset: 0

Views

Author

Henry Bottomley, Apr 27 2000

Keywords

Links

Crossrefs

Cf. A002516, A002517, A002518, A007379.

Programs

  • Mathematica
    a[n_] := a[n] = Which[ Mod[n, 7] == 0, 7*a[n/7], Mod[n, 7] == 1, n+1, Mod[n, 7] == 2, 7*(n-2)+7, Mod[n, 7] == 3, n+1, Mod[n, 7] == 4, 7*(n-4)+21, Mod[n, 7] == 5, n+1, Mod[n, 7] == 6, 7*(n-6)+35]; a[0] = 0; Table[a[n], {n, 0, 63}] (* Jean-François Alcover, Sep 24 2012 *)

Formula

a(7n)=7*a(n), a(7n+1)=7n+2, a(7n+2)=49n+7, a(7n+3)=7n+4, a(7n+4)=49n+21, a(7n+5)=7n+6, a(7n+6)=49n+35

A054790 Earliest sequence with a(a(n))=10n.

Original entry on oeis.org

0, 2, 10, 4, 30, 6, 50, 8, 70, 11, 20, 90, 13, 120, 15, 140, 17, 160, 19, 180, 100, 22, 210, 24, 230, 26, 250, 28, 270, 31, 40, 290, 33, 320, 35, 340, 37, 360, 39, 380, 300, 42, 410, 44, 430, 46, 450, 48, 470, 51, 60, 490, 53, 520, 55, 540, 57, 560, 59, 580, 500, 62, 610
Offset: 0

Views

Author

Henry Bottomley, Apr 27 2000

Keywords

Links

Crossrefs

Cf. A002516, A002517, A002518, A007379.

Programs

  • Mathematica
    a[0] = 0; a[n_] := Which[m = Mod[n, 20]; m == 0, 10*n-100, m == 9, n+2, m == 10, n+10, m == 11, 10*n-20, MemberQ[ {2, 4, 6, 8, 13, 15, 17, 19}, m], 10*n-10, True, n+1]; Table[ a[n], {n, 0, 62}] (* Jean-François Alcover, Sep 24 2012 *)

A054788 Earliest sequence with a(a(n))=8n.

Original entry on oeis.org

0, 2, 8, 4, 24, 6, 40, 9, 16, 56, 11, 80, 13, 96, 15, 112, 64, 18, 136, 20, 152, 22, 168, 25, 32, 184, 27, 208, 29, 224, 31, 240, 192, 34, 264, 36, 280, 38, 296, 41, 48, 312, 43, 336, 45, 352, 47, 368, 320, 50, 392, 52, 408, 54, 424, 57, 72, 440, 59, 464, 61, 480, 63, 496
Offset: 0

Views

Author

Henry Bottomley, Apr 27 2000

Keywords

Links

Crossrefs

Cf. A002516, A002517, A002518, A007379.

Programs

  • Mathematica
    nmax = 63; amax = 8*nmax; t = {{0, a[0] = 0}, {1, a[1] = 2}, {2, a[2]}}; While[ !FreeQ[t, a], t = Table[{n, a[n]}, {n, 0, nmax}]; n = Select[t, !IntegerQ[ #[[2]] ] &, 1][[1, 1]]; t2 = Union[ Flatten[ Append[ Select[ t, IntegerQ[ #[[2]] ] &], n]]]; an = If[n == 2, 8, Select[ Complement[ Range[ Max[t2] ], t2], Mod[#, 8] != 0 &, 1][[1]] ]; a[n] = an; While[ an < amax, an = a[n = an] = 8 n]]; Table[ a[n], {n, 0, nmax}] (* Jean-François Alcover, Jan 11 2012 *)

A054789 Earliest sequence with a(a(n)) = 9n.

Original entry on oeis.org

0, 2, 9, 4, 27, 6, 45, 8, 63, 18, 11, 90, 13, 108, 15, 126, 17, 144, 81, 20, 171, 22, 189, 24, 207, 26, 225, 36, 29, 252, 31, 270, 33, 288, 35, 306, 243, 38, 333, 40, 351, 42, 369, 44, 387, 54, 47, 414, 49, 432, 51, 450, 53, 468, 405, 56, 495, 58, 513, 60, 531, 62, 549
Offset: 0

Views

Author

Henry Bottomley, Apr 27 2000

Keywords

Links

Crossrefs

Cf. A002516, A002517, A002518, A007379, A008585.

Programs

  • Mathematica
    a[0] = 0; a[n_] := Which[m = Mod[n, 18]; m == 0, 9*n-81, m == 9, n+9, MemberQ[ {1, 3, 5, 7, 10, 12, 14, 16}, m], n+1, True, 9*n-9]; Table[ a[n], {n, 0, 62}] (* Jean-François Alcover, Sep 24 2012 *)
Showing 1-5 of 5 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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