This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A065710 Number of 2's in decimal expansion of 2^n. 19
 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 2, 2, 0, 2, 0, 0, 1, 1, 0, 2, 1, 1, 1, 1, 2, 1, 0, 0, 0, 1, 1, 0, 1, 4, 0, 3, 1, 2, 0, 1, 1, 3, 3, 3, 1, 2, 0, 1, 2, 1, 2, 2, 2, 3, 1, 3, 0, 2, 2, 3, 3, 2, 2, 4, 4, 4, 0, 1, 2, 4, 3, 1, 3, 6, 2, 0, 2, 4, 4, 4, 2, 3, 6, 2, 1, 5, 1, 2, 4, 4, 1, 2, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,19 COMMENTS 2^31 = 2147483648 so a(31) = 1. LINKS Harry J. Smith, Table of n, a(n) for n = 0..1000 MATHEMATICA Table[ Count[ IntegerDigits[2^n], 2], {n, 0, 100} ] PROG (PARI) Count(x, d)= { local(c=0, f); while (x>9, f=x-10*(x\10); if (f==d, c++); x\=10); if (x==d, c++); return(c) } { for (n=0, 1000, a=Count(2^n, 2); write("b065710.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 26 2009 (PARI) a(n) = #select(x->(x==2), digits(2^n)); \\ Michel Marcus, Jun 15 2018 CROSSREFS Cf. 0's A027870, 1's A065712, 3's A065714, 4's A065715, 5's A065716, 6's A065717, 7's A065718, 8's A065719, 9's A065744. Sequence in context: A244606 A273127 A103272 * A089799 A073464 A142242 Adjacent sequences:  A065707 A065708 A065709 * A065711 A065712 A065713 KEYWORD nonn,base AUTHOR Benoit Cloitre, Dec 04 2001 EXTENSIONS More terms from Robert G. Wilson v, Dec 07 2001 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 21 15:32 EDT 2019. Contains 323444 sequences. (Running on oeis4.)