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A265402
Fixed points of A265388: numbers n for which gcd{k=1..n-1} binomial(2*n, 2*k) = n.
3
11, 17, 23, 29, 43, 47, 53, 59, 67, 71, 73, 83, 89, 101, 103, 107, 109, 113, 127, 131, 137, 149, 151, 163, 167, 173, 179, 191, 193, 197, 223, 227, 233, 239, 241, 251, 257, 263, 269, 277, 281, 283, 293, 311, 317, 347, 349, 353, 359, 373, 383, 389, 397, 401, 409, 419, 431, 433, 443, 449, 457, 461, 463, 467, 479, 487, 491, 503
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range@ 504, GCD @@ Array[Function[k, Binomial[2 #, 2 k]], {# - 1}] == # &] (* Michael De Vlieger, Dec 11 2015 *)
PROG
(PARI) isok(n) = (n>1) && gcd(vector(n-1, k, binomial(2*n, 2*k))) == n; \\ Michel Marcus, Dec 08 2015, edited by Antti Karttunen, Dec 11 2015 (see A265388 for why).
CROSSREFS
Fixed points of A265388. Cf. also A265403.
Sequence in context: A280326 A160129 A275682 * A145481 A006621 A337359
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 08 2015
STATUS
approved