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.

A143852 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2-3-2, 2-5-2-3, 7-2-3-3, 2-2-5-11, 2-2-3-13, 2-7-3-5,..)).

Original entry on oeis.org

6, 8, 1, 16, 16, 13, 21, 20, 13, 34, 7, 17, 36, 37, 17, 27, 5, 13, 3, 29, 28, 6, 30, 8, 17, 66, 9, 1, 47, 52, 89, 8, 14, 77, 41, 81, 6, 31, 1, 1, 91, 8, 124, 13, 31, 13, 82, 17, 55, 69, 103, 10, 13, 100, 119, 18, 155, 6, 91, 40, 111, 11, 32, 55, 9, 10, 15, 37, 10, 115, 23, 124, 17
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7-3-5)=abs (-13) =13=a(6).
Abs (2-4-17-2)=abs(-21)=21=a(7).
Abs (3-2-19-2)=abs (-20)=20=a(8).
Abs (2-5-3-7)=abs (-13)=13=a(9).
Abs (2-11-23-2)=abs(-34)=34=a(10),
etc.

Links

Crossrefs

Cf. A141287, A141261, A136678, A143717.

Programs

  • Maple
    g:= proc(n) local F;
   F:= sort(ifactors(n)[2], (a,b) -> a[1]Robert Israel, Apr 25 2016
  • Mathematica
    Abs@ Total@ MapAt[Abs, Minus@ #, {1}] & /@ Partition[#, 4] &@ Flatten[FactorInteger /@ Range@ 134 /. {a_, b_} /; b == 1 :> {a}] (* Michael De Vlieger, Apr 25 2016 *)

Extensions

Corrected (10 replaced by 8) and extended by R. J. Mathar, Apr 18 2010

A144022 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2+3-2, 2-5+2-3, 7-2+3-3, 2-2+5-11, 2-2+3-13, 2-7+3-5,..)).

Original entry on oeis.org

0, 4, 5, 6, 10, 7, 13, 18, 7, 12, 3, 11, 22, 27, 11, 17, 1, 51, 9, 35, 32, 4, 26, 4, 11, 40, 3, 5, 43, 56, 85, 6, 12, 57, 35, 67, 0, 105, 3, 21, 67, 2, 42, 1, 55, 19, 88, 9, 49, 59, 97, 6, 9, 102, 87, 12, 49, 0, 101, 36, 107, 35, 26, 63, 15, 6, 97, 27, 6, 129, 33, 128, 21, 62, 121
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7+3-5)=abs (-7) =7=a(6).
Abs (2-4+17-2)=abs(13)=13=a(7).
Abs (3-2+19-2)=abs (18)=18=a(8).
Abs (2-5+3-7)=abs (-7)=7=a(9).
Abs (2-11+23-2)=abs(12)=12=a(10),
etc.

Crossrefs

Cf. A141287, A141261, A136678, A143717.

Extensions

Corrected (11 replaced by 9, 5 replaced by 6, 104 by 102) by R. J. Mathar, Apr 18 2010

A144076 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2*3-2, 2-5*2-3, 7-2*3-3, 2-2*5-11, 2-2*3-13, 2-7*3-5,..)).

Original entry on oeis.org

7, 11, 2, 19, 17, 24, 68, 37, 20, 253, 14, 40, 41, 44, 24, 90, 6, 4, 2, 28, 28, 9, 75, 13, 18, 77, 12, 2, 64, 52, 148, 13, 61, 736, 72, 104, 9, 4, 1, 60, 1026, 15, 3403, 24, 72, 12, 81, 88, 98, 252, 110, 15, 22, 199, 1750, 41, 206, 7, 88, 75, 222, 98, 87, 112, 8, 19, 64, 156
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7*3-5)=abs (-24) =24=a(6).
Abs (2-4*17-2)=abs(-68)=68=a(7).
Abs (3-2*19-2)=abs (-37)=37=a(8).
Abs (2-5*3-7)=abs (-20)=20=a(9).
Abs (2-11*23-2)=abs(-253)=253=a(10),
etc.

Crossrefs

Cf. A141287, A141261, A136678, A143717.

Extensions

Corrected (12 replaced by 52) by R. J. Mathar, Apr 18 2010

A144114 (1, 2, 3, 2^2, 5, 2*3, 7, 2^3, 3^2, 2*5, 11, 2^2*3, 13, 2*7, 3*5,..) becomes (abs(1-2^3-2, 2-5^2-3, 7-2^3-3, 2-2^5-11, 2-2^3-13, 2-7^3-5,..)).

Original entry on oeis.org

9, 26, 4, 41, 19, 346, 17179869184, 524287, 130, 895430243255237372246531, 242, 2198, 155, 272, 134, 1419862, 8, 524254, 0, 26, 28, 31, 2190, 48, 20, 8243, 30, 4, 387, 52, 3747, 127, 1220703121
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Nov 17 2008

Keywords

Examples

			Abs (2-7^3-5)=abs (-346) =346=a(6).
Abs (2-4^17-2)=abs(-17179869184)=17179869184=a(7).
Abs (3-2^19-2)=abs (-524287)=524287=a(8).
Abs (2-5^3-7)=abs (-130)=130=a(9),
etc.

Crossrefs

Cf. A141287, A141261, A136678, A143717.

Extensions

More terms from R. J. Mathar, Apr 18 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 1-5 of 5 results.

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