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 A347309 a(n) = gcd(b(n-1)+1, b(n)), where b is A347113. 2
 2, 5, 11, 23, 47, 5, 2, 3, 7, 3, 4, 3, 13, 9, 5, 2, 19, 13, 7, 8, 17, 5, 3, 5, 31, 21, 11, 3, 4, 3, 37, 25, 2, 29, 59, 17, 3, 2, 41, 83, 167, 5, 3, 2, 43, 29, 2, 3, 7, 19, 5, 23, 2, 3, 5, 61, 41, 7, 2, 53, 107, 43, 11, 7, 2, 67, 3, 4, 5, 71, 13, 3, 2, 3, 73, 3, 5, 2, 79, 53, 2, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS The definition of A347113 forbids a(n) to be 1. LINKS Michel Marcus, Table of n, a(n) for n = 2..10000 (terms 2..1000 from N. J. A. Sloane) MAPLE b:= proc() true end: g:= proc(n) option remember; local j, k; j:= g(n-1)+1; for k from 2 do if b(k) and k<>j and igcd(k, j)>1 then b(k):= false; return k fi od end: g(1):= 1: a:= n-> igcd(g(n-1)+1, g(n)): seq(a(n), n=2..100); # Alois P. Heinz, Sep 02 2021 MATHEMATICA b[_] = True; g[n_] := g[n] = Module[{j = g[n - 1] + 1, k}, For[k = 2, True, k++, If[ b[k] && k != j && GCD[k, j] > 1, b[k] = False; Return[k]]]]; g[1] = 1; a[n_] := GCD[g[n - 1] + 1, g[n]]; Table[a[n], {n, 2, 100}] (* Jean-François Alcover, May 06 2022, after Alois P. Heinz *) CROSSREFS Cf. A347113. Sequence in context: A192580 A075712 A349411 * A174162 A340799 A186253 Adjacent sequences: A347306 A347307 A347308 * A347310 A347311 A347312 KEYWORD nonn AUTHOR N. J. A. Sloane, Sep 01 2021 STATUS approved

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Last modified September 13 20:16 EDT 2024. Contains 375910 sequences. (Running on oeis4.)