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 A099427 a(1) = 1; for n > 1, a(n) = 1 + greatest common divisor of n and a(n-1). 3
 1, 2, 2, 3, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 6, 7, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4, 3, 2, 3, 2, 3, 4, 5, 2, 3, 2, 3, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(A060401(n)) = n + 1; a(A192489(n)) = 2. - Reinhard Zumkeller, Jul 02 2011 For n >= 3, a(n) == n+1 (mod 2). - Robert Israel, Jan 10 2017 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE a(9)=4 because 1+gcd(a(8),9)=1+gcd(3,9)=1+3. MAPLE f:= proc(n) option remember; 1 + igcd(n, procname(n-1)) end proc: f(1):= 1: map(f, [\$1..1000]); # Robert Israel, Jan 10 2017 MATHEMATICA a[1] = 1; a[n_] := a[n] = GCD[n, a[n - 1]] + 1; Table[ a[n], {n, 105}] (* Robert G. Wilson v, Nov 18 2004 *) nxt[{n_, a_}]:={n+1, GCD[n+1, a]+1}; Transpose[NestList[nxt, {1, 1}, 110]] [[2]] (* Harvey P. Dale, Nov 22 2014 *) PROG (Haskell) a099427 n = a099427_list !! (n-1) a099427_list = 1 : map (+ 1) (zipWith gcd [2..] a099427_list) -- Reinhard Zumkeller, Jun 23 2015, Jul 02 2011 CROSSREFS For position of first occurrence of n see A060401. Sequence in context: A185816 A324901 A295568 * A059964 A308050 A248147 Adjacent sequences:  A099424 A099425 A099426 * A099428 A099429 A099430 KEYWORD easy,nonn,nice AUTHOR Gaetan Polard (gaetan27(AT)hotmail.com), Nov 18 2004 EXTENSIONS Edited and extended by Robert G. Wilson v, Nov 18 2004 STATUS approved

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Last modified August 3 21:13 EDT 2021. Contains 346441 sequences. (Running on oeis4.)