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A058079
a(n) = p3, where {p1,p2,p3} are 3 consecutive primes with increasing order such that gcd(C(p3,p2), C(p2,p1)) = 1, where C is the binomial coefficient.
1
5, 7, 19, 23, 43, 73, 79, 107, 149, 151, 167, 173, 197, 199, 211, 271, 293, 313, 349, 367, 389, 409, 433, 439, 457, 467, 503, 509, 593, 619, 643, 647, 683, 773, 821, 823, 827, 863, 883, 887, 997, 1019, 1051, 1069, 1217, 1223
OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
73 is here because C(73,71) = 2628 = 4*9*73 and C(71,67) = 971635 = 71*23*17*7*5 are relatively prime.
MATHEMATICA
Select[Partition[Prime[Range[200]], 3, 1], GCD[Binomial[#[[3]], #[[2]]], Binomial[#[[2]], #[[1]]]]==1&][[;; , 3]] (* Harvey P. Dale, Feb 26 2023 *)
PROG
(PARI) is(n)=my(p=precprime(n-1), q=precprime(p-1)); gcd(binomial(n, p), binomial(p, q))==1 && isprime(n) && n>4 \\ Charles R Greathouse IV, Nov 13 2015
CROSSREFS
Sequence in context: A258655 A174362 A268608 * A076787 A332763 A094963
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 13 2000
EXTENSIONS
Name corrected by Charles R Greathouse IV, Nov 13 2015
STATUS
approved