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.

A036301 Numbers whose sum of even digits and sum of odd digits are equal.

Original entry on oeis.org

0, 112, 121, 134, 143, 156, 165, 178, 187, 211, 314, 336, 341, 358, 363, 385, 413, 431, 516, 538, 561, 583, 615, 633, 651, 718, 781, 817, 835, 853, 871, 1012, 1021, 1034, 1043, 1056, 1065, 1078, 1087, 1102, 1120, 1201, 1210, 1223, 1232, 1245, 1254, 1267, 1276, 1289, 1298
Offset: 1

Views

Author

Patrick De Geest, Dec 15 1998

Keywords

Crossrefs

Cf. A071650 (sum of odd digits minus sum of even digits).

Programs

  • Magma
    [ n: n in [0..1300] | (#A eq 0 select 0 else &+A) eq (#B eq 0 select 0 else &+B) where A is [ d: d in D | IsOdd(d) ] where B is [ d: d in D | IsEven(d) ] where D is Intseq(n) ];
    
  • Mathematica
    Select[Range[0,10000], Plus @@Select[IntegerDigits[ # ], OddQ]\[Equal]Plus @@Select[IntegerDigits[ # ], EvenQ]&] (* Zak Seidov, Feb 17 2005 *)
  • PARI
    select( is_A036301(n)=!vecsum(apply(t->(-1)^t*t,digits(n))), [0..1999]) \\ This defines the function is_A036301 = !A071650; the surrounding select(...) just serves as a check and illustration. - M. F. Hasler, Dec 09 2018
    A36301=[112]; A036301(n, L=#A36301)={while(n>L, A36301=concat(A36301, next_A036301(A36301[L], L, L+=1))); A36301[n]} \\ M. F. Hasler, Aug 11 2023
    next_A036301(N, L=#A36301, k=setsearch(A36301, N+1, 1)) = if(k>L, until( is_A036301(N+=1),); N, k, A36301[k], N+1) \\ next larger term: min { a(k) > N }. - M. F. Hasler, Aug 11 2023
    
  • Python
    def eodiff(n):
      digs = list(map(int, str(n)))
      return abs(sum(d for d in digs if d%2==0)-sum(d for d in digs if d%2==1))
    def aupto(lim): return [m for m in range(lim+1) if eodiff(m) == 0]
    print(aupto(1298)) # Michael S. Branicky, Feb 21 2021

Formula

This set A036301 = { n | A071650(n) = 0 }. - M. F. Hasler, Aug 11 2023

Extensions

Zero added by Zak Seidov, Nov 22 2010
Name edited by Michel Marcus, Jan 14 2021