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A214054 Least m>0 such that n!!+m and n-m have a common divisor > 1. 4
1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Clark Kimberling, Table of n, a(n) for n = 1..1000

EXAMPLE

For n=6: gcd(n!!+1,n-1) = 1 and gcd(n!!+2,n-2)=2, so that a(6)=2.

MATHEMATICA

b[n_]:=n!!; c[n_]:=n;

t=Table[m=1; While[GCD[b[n]+m, c[n]-m]==1, m++]; m, {n, 1, 200}] (* A214054 *)

Flatten[Position[t, 1]] (* A214585 *)

Flatten[Position[t, 2]] (* A214586 *)

CROSSREFS

Cf. A214585, A214586.

Sequence in context: A318749 A050330 A205788 * A330739 A076398 A086257

Adjacent sequences:  A214051 A214052 A214053 * A214055 A214056 A214057

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jul 21 2012

STATUS

approved

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Last modified October 1 08:39 EDT 2020. Contains 337442 sequences. (Running on oeis4.)