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 1-2 of 2 results.

A257869 Nonnegative integers with an equal number of occurrences of all trits in balanced ternary representation.

Original entry on oeis.org

6, 8, 136, 138, 144, 154, 156, 160, 164, 168, 170, 180, 186, 188, 208, 210, 214, 218, 222, 224, 232, 236, 248, 258, 260, 266, 288, 294, 296, 312, 314, 320, 3406, 3412, 3414, 3430, 3432, 3438, 3484, 3486, 3492, 3510, 3568, 3574, 3576, 3592, 3594, 3600, 3622
Offset: 1

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Author

Alois P. Heinz, May 11 2015

Keywords

Examples

			6 = 1L0_bal3, 8 = 10L_bal3, 136 = 1LL001_bal3, 138 = 1LL010_bal3, 144 = 1LL100_bal3, where L represents (-1).
		

Crossrefs

Subsequence of A174658.

Programs

  • Maple
    p:= proc(n) local d, m, r; m:=n; r:=0;
          while m>0 do
            d:= irem(m, 3, 'm');
            if d=2 then m:=m+1 fi;
            r:= r+x^d
          od;
          simplify(r/(1+x+x^2))::integer
        end:
    a:= proc(n) option remember; local k;
          for k from 1+`if`(n=1, 0, a(n-1)) by 1
          while not p(k) do od; k
        end:
    seq(a(n), n=1..70);
  • Python
    def a(n):
        s=[]
        x=0
        while n>0:
            x=n%3
            n//=3
            if x==2:
                x=-1
                n+=1
            s.append(x)
        return s
    print([n for n in range(1, 5001) if a(n).count(1)==a(n).count(-1) and a(n).count(-1)==a(n).count(0)]) # Indranil Ghosh, Jun 07 2017

A257867 Nonnegative integers n such that in balanced ternary representation the number of occurrences of each trit doubles when n is squared.

Original entry on oeis.org

314, 942, 2824, 2826, 2854, 3074, 3130, 3212, 8066, 8090, 8096, 8170, 8224, 8324, 8426, 8450, 8472, 8478, 8480, 8512, 8534, 8562, 8578, 8588, 8656, 9222, 9224, 9390, 9404, 9636, 9638, 24198, 24206, 24270, 24288, 24510, 24670, 24672, 24674, 24676, 24802, 24972
Offset: 1

Views

Author

Alois P. Heinz, May 11 2015

Keywords

Examples

			942 is in the sequence because 942 = 110L0L0_bal3 and 942^2 = 887364 = 1LL0001L1L0100_bal3, where L represents (-1).
		

Crossrefs

Programs

  • Maple
    p:= proc(n) local d, m, r; m:=n; r:=0;
          while m>0 do
            d:= irem(m,3,'m');
            if d=2 then m:=m+1 fi;
            r:=r+x^d
          od; r
        end:
    a:= proc(n) option remember; local k;
          for k from 1+`if`(n=1, 0, a(n-1))
          while p(k)*2<>p(k^2) do od; k
        end:
    seq(a(n), n=1..50);
  • Python
    def a(n):
        s=[]
        x=0
        while n>0:
            x=n%3
            n//=3
            if x==2:
                x=-1
                n+=1
            s.append(x)
        return s
    print([n for n in range(1, 25001) if a(n**2).count(-1)==2*a(n).count(-1) and a(n**2).count(1)==2*a(n).count(1) and a(n**2).count(0)==2*a(n).count(0)]) # Indranil Ghosh, Jun 07 2017
Showing 1-2 of 2 results.