A001357 Powers of 2 written in base 9.

1, 2, 4, 8, 17, 35, 71, 152, 314, 628, 1357, 2725, 5551, 12212, 24424, 48848, 108807, 218715, 438531, 878162, 1867334, 3845668, 7802447, 16705005, 34511011, 70122022, 150244044, 310488088, 621087187, 1342185385, 2684381781, 5478773672, 12068657454, 24148426018

Offset: 0

Author

N. J. A. Sloane

Keywords

• easy
• base
• nonn

References

• Archimedeans Problems Drive, Eureka, 14 (1951), 13.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1000 (first 301 terms from T. D. Noe)

Programs

Maple

b:= proc(n) local m; m:= n; "";
      while m>0 do irem(m, 9, 'm'), % od;
      parse(cat(%))
    end:
a:= n-> b(2^n):
seq(a(n), n=0..42);  # Alois P. Heinz, Aug 21 2019

Mathematica

Table[FromDigits[IntegerDigits[2^n, 9]], {n, 0, 30}] (* T. D. Noe, Jun 28 2012 *)

PARI

{for(ixp=0, 34,
casi = 2^ixp; cvst=0;
while(casi != 0,
cvd = casi%9; cvst=10*cvst + cvd + 1; casi = (casi - cvd) / 9 );
while(cvst !=0,
ptch = cvst%10; print1(ptch-1); cvst = (cvst - ptch) / 10 );
print1(", "))} /* Douglas Latimer, Apr 23 2012 */

Extensions

More terms from Douglas Latimer, Apr 16 2012