A008559 - OEIS

A008559

a(1)=2; thereafter, convert a(n-1) from base 10 to base 2 but regard the result as a base 10 number.

2, 10, 1010, 1111110010, 1000010001110100011000101111010

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OFFSET

1,1

COMMENTS

The previous number is converted to binary digits and then the digits are regarded as decimal digits in the next number in the sequence. - Michael Somos, May 16 2014

The next term has 100 digits. - Harvey P. Dale, Jul 16 2011

The number of decimal digits of a(n) is A242347(n). - Robert G. Wilson v, Jul 10 2013

Log(a(n)) / log(a(n-1)) = ~1/log_10(2) = A020862. - Robert G. Wilson v, Jul 10 2013

REFERENCES

Clifford Pickover, Mazes for the Mind, St. Martin's Press, NY, 1992, p. 350.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..7

MAPLE

f:=proc(n) local i, j, r; i:=convert(n, base, 2); j:=add(i[r]*10^(r-1), r=1..nops(i)); end;

g:=proc(n, M) global f; local a, b, t1; a:=n; t1:=[a]; for i from 1 to M do b:=f(a); t1:=[op(t1), b]; a:=b; od; t1; end; g(2, 5); # N. J. A. Sloane, Jul 14 2015

MATHEMATICA

NestList[FromDigits[IntegerDigits[#, 2]]&, 2, 5] (* Harvey P. Dale, Jul 16 2011 *)

PROG

(Python)

A008559_list = [2]

for _ in range(5):

....A008559_list.append(int(bin(A008559_list[-1])[2:]))

# Chai Wah Wu, Dec 26 2014

CROSSREFS

Cf. A006937 (essentially the same sequence).

For initial terms 2 through 12 see A008559, A006938, A260025, A260024, A260026, A260027, A260028, A260029, A008559 (again), A006938 (again), A260030 respectively.

Sequence in context: A255587 A137890 A074333 * A245728 A171485 A291882

Adjacent sequences: A008556 A008557 A008558 * A008560 A008561 A008562

KEYWORD

nonn,base,nice

AUTHOR

N. J. A. Sloane

EXTENSIONS

Comment corrected by Chai Wah Wu, Dec 26 2014

STATUS

approved