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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A061472 First (leftmost) digit - second digit + third digit - fourth digit .... = 3.

Original entry on oeis.org

3, 30, 41, 52, 63, 74, 85, 96, 102, 113, 124, 135, 146, 157, 168, 179, 201, 212, 223, 234, 245, 256, 267, 278, 289, 300, 311, 322, 333, 344, 355, 366, 377, 388, 399, 410, 421, 432, 443, 454, 465, 476, 487, 498, 520, 531, 542, 553, 564, 575, 586, 597, 630
Offset: 1

Views

Author

Amarnath Murthy, May 05 2001

Keywords

Examples

			124 is in the sequence since 1 - 2 + 4 = 3.

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882, A225693.

Programs

  • Maple
    A225693:= proc(n) local L,m,i;
  L:= convert(n,base,10);
  m:= nops(L);
  add(L[i]*(-1)^(m-i),i=1..m);
end proc:
select(A225693=3, [$1..1000]); # Robert Israel, Jun 12 2019
  • Mathematica
    aQ[n_] := Differences[Total @ Take[IntegerDigits[n], {#, -1, 2}] & /@ {2, 1}][[1]] == 3; Select[Range[1000], aQ] (* Amiram Eldar, Jun 12 2019 *)
Select[Range[1000],Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]==3&] (* Harvey P. Dale, May 16 2020 *)
  • PARI
    isok(n) = my(d=digits(n)); sum(k=1, #d, (-1)^(k+1)*d[k]) == 3; \\ Michel Marcus, Jun 12 2019

Formula

A225693(n) = 3. - Robert Israel, Jun 12 2019

Extensions

More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 14 2001

A061473 First (leftmost) digit - second digit + third digit - fourth digit .... = 4.

Original entry on oeis.org

4, 40, 51, 62, 73, 84, 95, 103, 114, 125, 136, 147, 158, 169, 202, 213, 224, 235, 246, 257, 268, 279, 301, 312, 323, 334, 345, 356, 367, 378, 389, 400, 411, 422, 433, 444, 455, 466, 477, 488, 499, 510, 521, 532, 543, 554, 565, 576, 587, 598, 620, 631, 642
Offset: 1

Views

Author

Amarnath Murthy, May 05 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Select[Range[700],Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]==4&] (* Harvey P. Dale, Jan 27 2014 *)

Extensions

More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 14 2001

A061474 First (leftmost) digit - second digit + third digit - fourth digit .... = 5.

Original entry on oeis.org

5, 50, 61, 72, 83, 94, 104, 115, 126, 137, 148, 159, 203, 214, 225, 236, 247, 258, 269, 302, 313, 324, 335, 346, 357, 368, 379, 401, 412, 423, 434, 445, 456, 467, 478, 489, 500, 511, 522, 533, 544, 555, 566, 577, 588, 599, 610, 621, 632, 643, 654, 665, 676
Offset: 1

Views

Author

Amarnath Murthy, May 05 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Select[Range[1000],Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]==5&] (* Harvey P. Dale, Jul 12 2015 *)

Extensions

More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 14 2001

A061477 First (leftmost) digit - second digit + third digit - fourth digit .... = 8.

Original entry on oeis.org

8, 80, 91, 107, 118, 129, 206, 217, 228, 239, 305, 316, 327, 338, 349, 404, 415, 426, 437, 448, 459, 503, 514, 525, 536, 547, 558, 569, 602, 613, 624, 635, 646, 657, 668, 679, 701, 712, 723, 734, 745, 756, 767, 778, 789, 800, 811, 822, 833, 844, 855, 866
Offset: 1

Views

Author

Amarnath Murthy, May 05 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Select[Range[1000],Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]==8&] (* Harvey P. Dale, Oct 11 2012 *)

Extensions

More terms from Robert G. Wilson v, May 10 2001 and from Larry Reeves (larryr(AT)acm.org), May 15 2001

A061872 |First digit - second digit + third digit - fourth digit ...| = 3.

Original entry on oeis.org

3, 14, 25, 30, 36, 41, 47, 52, 58, 63, 69, 74, 85, 96, 102, 113, 124, 135, 140, 146, 151, 157, 162, 168, 173, 179, 184, 195, 201, 212, 223, 234, 245, 250, 256, 261, 267, 272, 278, 283, 289, 294, 300, 311, 322, 333, 344, 355, 360, 366, 371, 377, 382, 388, 393
Offset: 1

Views

Author

Robert G. Wilson v, May 10 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[ [ 2k - 1 ] ] ], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[ [ 2k ] ] ], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ] ] == 3, Print[ n ] ], {n, 1, 1000} ]
fdsdQ[n_]:=Module[{idn=IntegerDigits[n],o,e},o=Take[idn,{1,-1,2}];e= Take[ idn,{2,-1,2}];Abs[Total[o]-Total[e]]==3]; Select[Range[400],fdsdQ] (* Harvey P. Dale, Nov 01 2011 *)

A061873 Numbers n such that |first digit - second digit + third digit - fourth digit ...| = 4.

Original entry on oeis.org

4, 15, 26, 37, 40, 48, 51, 59, 62, 73, 84, 95, 103, 114, 125, 136, 147, 150, 158, 161, 169, 172, 183, 194, 202, 213, 224, 235, 246, 257, 260, 268, 271, 279, 282, 293, 301, 312, 323, 334, 345, 356, 367, 370, 378, 381, 389, 392, 400, 411, 422, 433, 444, 455
Offset: 1

Views

Author

Robert G. Wilson v, May 10 2001

Keywords

Comments

All terms == 4 or 7 (mod 11). - Robert Israel, Jun 03 2016

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Maple
    F:= proc(n) option remember;
      -procname(floor(n/10)) + (n mod 10)
    end proc:
for j from 0 to 9 do F(j):= j od:
select(abs @ F = 4, [$1..1000]); # Robert Israel, Jun 03 2016
  • Mathematica
    Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[ [ 2k - 1 ] ] ], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[ [ 2k ] ] ], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ] ] == 4, Print[ n ] ], {n, 1, 1000} ]
  • Python
    def ok(n): return abs(sum((-1)**i*int(d) for i, d in enumerate(str(n))))==4
print(list(filter(ok, range(456)))) # Michael S. Branicky, Apr 15 2021

A061875 |First digit - second digit + third digit - fourth digit ...| = 6.

Original entry on oeis.org

6, 17, 28, 39, 60, 71, 82, 93, 105, 116, 127, 138, 149, 170, 181, 192, 204, 215, 226, 237, 248, 259, 280, 291, 303, 314, 325, 336, 347, 358, 369, 390, 402, 413, 424, 435, 446, 457, 468, 479, 501, 512, 523, 534, 545, 556, 567, 578, 589, 600, 611, 622, 633, 644
Offset: 1

Views

Author

Robert G. Wilson v, May 10 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[[ 2k - 1 ] ] ], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[[ 2k ] ] ], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ] ] == 6, Print[ n ] ], {n, 1, 1000} ]
Select[Range[700],Abs[Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]]==6&] (* Harvey P. Dale, May 21 2020 *)
  • Python
    def ok(n): return abs(sum(int(d)*(-1)**i for i, d in enumerate(str(n))))==6
print(list(filter(ok, range(645)))) # Michael S. Branicky, Jun 17 2021

A061876 |First digit - second digit + third digit - fourth digit ...| = 7.

Original entry on oeis.org

7, 18, 29, 70, 81, 92, 106, 117, 128, 139, 180, 191, 205, 216, 227, 238, 249, 290, 304, 315, 326, 337, 348, 359, 403, 414, 425, 436, 447, 458, 469, 502, 513, 524, 535, 546, 557, 568, 579, 601, 612, 623, 634, 645, 656, 667, 678, 689, 700, 711, 722, 733, 744
Offset: 1

Views

Author

Robert G. Wilson v, May 10 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[[ 2k - 1 ] ]], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[[ 2k ] ]], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ]] == 7, Print[ n ]], {n, 1, 1000} ]
Select[Range[1000],Abs[Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]]==7&] (* Harvey P. Dale, Jan 05 2013 *)

A061877 |First digit - second digit + third digit - fourth digit ...| = 8.

Original entry on oeis.org

8, 19, 80, 91, 107, 118, 129, 190, 206, 217, 228, 239, 305, 316, 327, 338, 349, 404, 415, 426, 437, 448, 459, 503, 514, 525, 536, 547, 558, 569, 602, 613, 624, 635, 646, 657, 668, 679, 701, 712, 723, 734, 745, 756, 767, 778, 789, 800, 811, 822, 833, 844, 855
Offset: 1

Views

Author

Robert G. Wilson v, May 10 2001

Keywords

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Do[ a = IntegerDigits[ n ]; l = Length[ a ]; e = o = {}; Do[ o = Append[ o, a[[ 2k - 1 ]]], {k, 1, l/2 + .5} ]; Do[ e = Append[ e, a[[ 2k ] ]], {k, 1, l/2} ]; If[ Abs[ Apply[ Plus, o ] - Apply[ Plus, e ]] == 8, Print[ n ]], {n, 1, 1000} ]
Select[Range[1000],Abs[Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]]==8&] (* Harvey P. Dale, Jan 28 2019 *)
  • Python
    def ok(n): return abs(sum((-1)**i*int(d) for i, d in enumerate(str(n))))==8
print(list(filter(ok, range(860)))) # Michael S. Branicky, Aug 19 2021

A061879 First (leftmost) digit - second digit + third digit - fourth digit .... = 10.

Original entry on oeis.org

109, 208, 219, 307, 318, 329, 406, 417, 428, 439, 505, 516, 527, 538, 549, 604, 615, 626, 637, 648, 659, 703, 714, 725, 736, 747, 758, 769, 802, 813, 824, 835, 846, 857, 868, 879, 901, 912, 923, 934, 945, 956, 967, 978, 989, 1090, 2080, 2091, 2190, 3070
Offset: 1

Views

Author

Larry Reeves (larryr(AT)acm.org), May 15 2001

Keywords

Comments

Differs from A060978 at the 47th term.

Links

Crossrefs

Cf. A008593, A060978-A060980, A060982, A061470-A061479, A061870-A061882.

Programs

  • Mathematica
    Select[Range[3500],Total[Times@@@Partition[Riffle[IntegerDigits[#],{1,-1},{2,-1,2}],2]]==10&] (* Harvey P. Dale, Apr 30 2016 *)
  • PARI
    isok(n) = {digs = digits(n); return (sum(i=1, #digs, (-1)^(i+1)*digs[i]) == 10);} \\ Michel Marcus, Jul 17 2013
Previous Showing 11-20 of 27 results. Next

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