OFFSET
1,1
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..5200
EXAMPLE
a(7)= 107 which is 28th prime. prime(28)-3*28= 107-84= 23: prime(28)+3*28= 107+84= 191: 23 and 191 both are primes.
a(9)= 173 which is 40th prime. prime(40)-3*40= 173-120= 53: prime(40)+3*40= 173+120= 293: 53 and 293 both are primes.
MAPLE
KD := proc() local a, b, d; a:= ithprime(n); b:= abs(a-3*n); d:=(a+3*n); if isprime(b) and isprime(d) then RETURN (a); fi; end: seq(KD(), n=1..500);
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Nov 09 2013
STATUS
approved