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A265394 Positions of records in A265388. 4
1, 2, 3, 6, 7, 15, 19, 31, 37, 79, 97, 139, 157, 199, 211, 229, 271, 307, 331, 337, 367, 379, 439, 499, 547, 577, 601, 607, 619, 661, 691, 727, 811, 829, 877, 937, 967, 997, 1009, 1069, 1171, 1237, 1279, 1297, 1399, 1429, 1459, 1531, 1609, 1627, 1657, 1759, 1867, 2011, 2029, 2089, 2131, 2137, 2179, 2221, 2281, 2311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Question: Apart from a(1)=1, a(4)=6 and a(6)=15, are all other terms primes? See also comments in A265395 & A265396.

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..192

PROG

(PARI) lista(nn) = {r = 0; for (n=1, nn, nr = gcd(vector(n-1, k, binomial(2*n, 2*k))); if (nr > r, print1(n, ", "); r = nr); ); } \\ Michel Marcus, Dec 08 2015

CROSSREFS

Cf. A265388.

Cf. A265395 (gives the record values), A265396.

Sequence in context: A245479 A294524 A032882 * A125167 A137604 A034901

Adjacent sequences:  A265391 A265392 A265393 * A265395 A265396 A265397

KEYWORD

nonn

AUTHOR

Antti Karttunen, Dec 08 2015

STATUS

approved

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Last modified October 22 03:04 EDT 2019. Contains 328315 sequences. (Running on oeis4.)