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.

A303500 The smallest positive even integer that can be written with n digits in base 3/2.

Original entry on oeis.org

2, 21, 210, 2101, 21011, 210110, 2101100, 21011000, 210110001, 2101100011, 21011000110, 210110001101, 2101100011010, 21011000110100, 210110001101001, 2101100011010011, 21011000110100110, 210110001101001101
Offset: 0

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Author

Tanya Khovanova and PRIMES STEP Senior group, May 09 2018

Keywords

Comments

a(n) is a prefix of a(n+1).
The smallest, not necessarily even, integer in base 3/2 with n digits is a(n-1) with 0 added at the end.

Examples

			The number 5 in base 3/2 is 22, and the number 6 is 210. Therefore, 210 is the smallest even integer with 3 digits in base 3/2.
		

Crossrefs

See A024629 for the base-3/2 expansion of n.

Programs

  • Maple
    roll32 := proc(L)
        local piv,L1 ;
        piv := 1;
        L1 := subsop(piv=op(piv,L)+1,L) ;
        while op(piv,L1) >= 3 do
            L1 := [seq(0,i=1..piv), op(piv+1,L1)+1, seq(op(i,L1),i=piv+2..nops(L1))] ;
            piv := piv+1 ;
        end do:
        L1 ;
    end proc:
    from32 := proc(L)
        add( op(i,L)*(3/2)^(i-1),i=1..nops(L)) ;
    end proc:
    A303500 := proc(n)
        local dgs ;
        dgs := [seq(0,i=1..n-1),1] ;
        while not type(from32(dgs),'even') do
            dgs := roll32(dgs) ;
        end do:
        dgs := ListTools[Reverse](dgs) ;
        digcatL(%) ;
    end proc: # R. J. Mathar, Jun 25 2018

Formula

a(n) = A024629(A305498(n)). - R. J. Mathar, Jun 25 2018