This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A156147 a(n+1) = round( c(n)/2 ), where c(n) is the concatenation of all preceding terms a(1)...a(n) and a(1)=1. 4
 1, 1, 6, 58, 5829, 58292915, 5829291479146458, 58292914791464577914645739573229, 5829291479146457791464573957322929146457395732288957322869786615 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Originally, round( c/2 ) was formulated as "rank of c in the sequence of odd resp. even (positive) numbers". The sequence has some characteristics reminiscent of Thue-Morse type sequences. It "converges" to a non-periodic sequence of digits: all but the last digit of a given term will remain the initial digits of all subsequent terms. - M. F. Hasler It's interesting that the number of digits of a(k) for k>2 equals to 2^(k-3). - Farideh Firoozbakht LINKS M. F. Hasler et al., Table of n, a(n) for n = 1..12 E. Angelini, Rang dans les Pairs/Impairs E. Angelini, Rang dans les Pairs/Impairs [Cached copy, with permission] E. Angelini et al., Rank of n in the Odd/Even sequence and follow-up messages on the SeqFan list, Feb 03 2009 MAPLE rank:= n-> `if`(irem(n, 2)=0, n/2, (n+1)/2): a:= proc(n) option remember; if n=1 then 1 else rank(parse(cat(seq(a(j), j=1..n-1)))) fi end: seq(a(n), n=1..10);  # Alois P. Heinz MATHEMATICA a[1]=1; a[n_]:=a[n]=(v={}; Do[v= Join[v, IntegerDigits[a[k]]], {k, n-1}]; Floor[(1+FromDigits[v])/2]) (* Farideh Firoozbakht *) PROG (PARI) A156147(n)={local(a=1, t=1); while(n-->1, t=round(1/2*a=eval(Str(a, t)))); t} /* M. F. Hasler */ CROSSREFS Cf. A156146 (other starting values). Sequence in context: A302922 A274985 A034982 * A024269 A224757 A114501 Adjacent sequences:  A156144 A156145 A156146 * A156148 A156149 A156150 KEYWORD base,easy,nonn AUTHOR Eric Angelini, Alois P. Heinz, Farideh Firoozbakht and M. F. Hasler, Feb 04 2009 EXTENSIONS Typos fixed by Charles R Greathouse IV, Oct 28 2009 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 August 18 08:57 EDT 2019. Contains 326077 sequences. (Running on oeis4.)