OFFSET
1,1
COMMENTS
A179675(n) = smallest m such that a(m) = n-th odd prime. - Reinhard Zumkeller, Jul 23 2010
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
MATHEMATICA
a[n_] := For[k = 3, True, k++, If[CoprimeQ[k, n, n+1], Return[k]]]; Table[a[n], {n, 1, 101}] (* Jean-François Alcover, Sep 20 2012 *)
PROG
(Haskell)
a053670 n = head [x | x <- [3, 5 ..],
n `gcd` x == 1, (n + 1) `gcd` x == 1]
-- Reinhard Zumkeller, Dec 28 2012
(PARI) a(n)=my(N=n*(n+1), k=2); while(gcd(k++, N)>1, ); k \\ Charles R Greathouse IV, Nov 10 2015
(Python)
from math import gcd
def a(n):
k, m = 3, n*(n+1)
while gcd(k, m) != 1: k += 2
return k
print([a(n) for n in range(1, 102)]) # Michael S. Branicky, Sep 25 2021
CROSSREFS
KEYWORD
nonn,nice,easy
AUTHOR
Henry Bottomley, Feb 15 2000
EXTENSIONS
More terms from Andrew Gacek (andrew(AT)dgi.net), Feb 21 2000 and James A. Sellers, Feb 22 2000
STATUS
approved