A080389 Numbers n such that gcd( n+1, binomial(n, floor(n/2)) ) = 1.

1, 2, 3, 4, 6, 7, 8, 10, 12, 15, 16, 18, 20, 22, 24, 26, 28, 30, 31, 36, 40, 42, 46, 48, 52, 54, 56, 58, 60, 63, 64, 66, 70, 72, 74, 78, 80, 82, 88, 96, 100, 102, 106, 108, 112, 114, 118, 120, 124, 126, 127, 130, 132, 136, 138, 148, 150, 156, 162, 166, 168, 170, 172, 178

Offset

1,2

Links

Table of n, a(n) for n=1..64.

Mathematica

Select[Range@ 180, CoprimeQ[# + 1, Binomial[#, Floor[#/2]]] &] (* Michael De Vlieger, Jul 30 2017 *)

Prog

(PARI) for(n=1, 199, if(gcd(n+1, binomial(n, n\2))==1, print1(n, ", "))); \\ Joerg Arndt, Jul 30 2017

Crossrefs

Sequence in context: A257282 A336488 A221178 * A359755 A226038 A181062

Adjacent sequences: A080386 A080387 A080388 * A080390 A080391 A080392

Keyword

nonn,easy,less

Author

Labos Elemer, Mar 12 2003

Extensions

Name corrected by Joerg Arndt, Jul 30 2017

Status

approved