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 1-4 of 4 results.

A144123 (0, 1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13,..) becomes (4, 6, 8, 9, 10^12, 14, 15*16, 18, 20^21, 22^24, 25*26, 27, 28^30*32, 33, ..).

Original entry on oeis.org

4, 6, 8, 9, 1000000000000, 14, 240, 18, 2097152000000000000000000000, 165251092644282265779977014214656, 650, 27, 831554883865300668552224606420411230629920768, 33, 1190, 1368
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			10^12=1000000000000=a(5).
14=a(6).
15*16=240=a(7).
20^21=2097152000000000000000000000,
etc.

Crossrefs

Cf. A002808, A136740, A136811, A143716.

Extensions

Corrected (18 inserted) and extended by R. J. Mathar, Apr 28 2010

A144136 (0=0, 1=1, 2=2, 3=3, 4=2^2, 5=5, 6=2*3, 7=7, 8=2^3, 9=3^2, 10=2*5, 11=11, 12=2^2*3, ...) becomes (0+0+1, 1+2+2, 3+3+4, 2+2+5, 5+6+2, 3+7+7, 8+2+3, 9+3+2, 10+2+5, 11+11+12, 2+2+3, ...).

Original entry on oeis.org

1, 5, 10, 9, 13, 17, 13, 14, 17, 34, 7, 40, 24, 24, 23, 37, 24, 41, 28, 32, 36, 49, 31, 33, 42, 34, 11, 88, 10, 94, 40, 48, 54, 48, 7, 76, 59, 55, 45, 87, 47, 93, 48, 59, 53, 72, 97, 56, 59, 9, 71, 56, 119, 59, 63, 69, 67, 80, 90, 121, 10, 184, 96, 12, 72, 83, 71, 145, 72, 89, 95
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			2 + 2 + 3 = 7 = a(11),
13 + 13 + 14 = 40 = a(12),
2 + 7 + 15 = 24 = a(13),
3 + 5 + 16 = 24 = a(14),
2 + 4 + 17 = 23 = a(15),
17 + 18 + 2 = 37 = a(16),
3 + 2 + 19 = 24 = a(17),
etc.

Crossrefs

Cf. A002808, A136740, A136811, A143716.

Programs

  • Maple
    pflat := proc(nmax) local a, ifs, n, p, c ; a := [0,0,1,1] ; for n from 2 to nmax do a := [op(a),n] ; ifs := ifactors(n)[2] ; for p in ifs do a := [op(a),op(1,p)] ; if op(2,p) > 1 then a := [op(a),op(2,p)] ; fi; od: od: a ; end: L := pflat(300) ; for n from 1 to nops(L)-3 by 3 do printf("%d,", op(n,L)+op(n+1,L)+op(n+2,L) ) ; end do: # R. J. Mathar, Apr 29 2010

Extensions

All numbers after a(14) corrected by R. J. Mathar, Apr 29 2010

A144153 (0=0, 1=1, 2=2, 3=3, 4=2^2, 5=5, 6=2*3, 7=7, 8=2^3, 9=3^2, 10=2*5, 11=11, 12=2^2*3, ...) becomes (0*0*1, 1*2*2, 3*3*4, 2*2*5, 5*6*2, 3*7*7, 8*2*3, 9*3*2, 10*2*5, 11*11*12, 2*2*3, ...).

Original entry on oeis.org

0, 4, 36, 20, 60, 147, 48, 54, 100, 1452, 12, 2366, 210, 240, 136, 612, 114, 760, 210, 462, 506, 1104, 225, 260, 702, 252, 28, 25230, 30, 30752, 330, 1122, 1190, 1260, 12, 2738, 1444, 1521, 240, 8405, 252, 12943, 176, 1485, 460, 2162, 4512, 588, 700, 20
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			2*2*3 = 12 = a(11),
13*13*14 = 2366 = a(12),
2*7*15 = 210 = a(13),
3*5*16 = 240 = a(14),
2*4*17 = 136 = a(15),
17*18*2 = 612 = a(16),
3*2*19 = 114 = a(17),
etc.

Crossrefs

Cf. A002808, A136740, A136811, A143716.

Programs

  • Maple
    pflat2 := proc(nmax) local a, ifs, n, p, c ; a := [0,0,1,1] ; for n from 2 to nmax do ifs := ifactors(n)[2] ; a := [op(a),n] ; for p in ifs do # a := [op(a), op(1, p)] ; a := [op(a),op(1, p)] ; if op(2, p) > 1 then a := [op(a), op(2, p)] ; fi; od: od: a ; end proc: pL := pflat2(100) ; for n from 1 to nops(pL)-3 by 3 do printf("%d,", op(n, pL)*op(n+1, pL)*op(n+2,pL) ) ; od: # R. J. Mathar, Apr 14 2010

Extensions

Terms from a(18) on replaced by R. J. Mathar, Apr 14 2010

A144158 (1=1, 2=2, 3=3, 4=2^2, 5=5, 6=2*3, 7=7, 8=2^3, 9=3^2, 10=2*5, 11=11, 12=2^2*3, 13=13, ...) becomes (1*1*2, 2*3*3, 4*2*2, 5*5*6, 2*3*7, 7*8*2, 3*9*3, 2*10*2, 5*11*11, 12*2*2, 3*13*13, ...).

Original entry on oeis.org

2, 18, 16, 150, 42, 112, 81, 40, 605, 48, 507, 196, 225, 128, 5202, 12, 7220, 20, 441, 484, 12696, 18, 250, 676, 243, 112, 5887, 180, 4805, 320, 1089, 1156, 1225, 144, 222, 2812, 2223, 1040, 615, 3444, 903, 3784, 990, 30, 2116, 106032, 24, 686, 500, 306
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			3*13*13 = 507 = a(11),
14*2*7 = 196 = a(12),
15*3*5 = 225 = a(13),
16*2*4 = 128 = a(14),
17*17*18 = 5202 = a(15),
2*3*2 = 12 = a(16),
19*19*20 = 7220 = a(17),
etc.

Crossrefs

Cf. A141186, A136740, A136811, A143717.

Programs

  • Maple
    pflat := proc(nmax) local a, ifs, n, p, c ; a := [1,1] ; for n from 2 to nmax do a := [op(a),n] ; ifs := ifactors(n)[2] ; for p in ifs do a := [op(a),op(1,p)] ; if op(2,p) > 1 then a := [op(a),op(2,p)] ; fi; od: od: a ; end: L := pflat(300) ; for n from 1 to nops(L)-3 by 3 do printf("%d,", op(n,L)*op(n+1,L)*op(n+2,L) ) ; end do: # R. J. Mathar, Apr 29 2010

Extensions

a(37) and terms after a(46) corrected by R. J. Mathar, Apr 29 2010
Showing 1-4 of 4 results.

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