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.

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

Crossrefs

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