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approved
a(2)=4 since 3*prime(4) + prime(5) - 3 = 3*7 + 11 - 3 = 29 is prime.
proposed
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proposed
Robert Israel, <a href="/A099466/b099466.txt">Table of n, a(n) for n = 1..10000</a>
P:= select(isprime, [2, seq(i, i=3..10^4, 2)]):
select(n -> isprime(3*P[n]+P[n+1]-3), [$1..nops(P)-1]); # Robert Israel, Nov 29 2017
approved
editing
_Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), _, Nov 18 2004
Corrected and extended by _Rick L. Shepherd (rshepherd2(AT)hotmail.com), _, Nov 24 2004
Numbers n such that 3*prime(n) + prime(n+1) - 3 is prime.
2, 3, 4, 5, 6, 7, 11, 12, 13, 14, 15, 19, 20, 22, 25, 30, 31, 33, 34, 36, 37, 38, 44, 45, 47, 49, 53, 55, 58, 59, 60, 63, 66, 67, 73, 79, 83, 87, 91, 93, 95, 98, 105, 107, 113, 115, 118, 122, 123, 127, 131, 135, 141, 144, 145, 147, 150, 153, 160, 162, 165, 167, 172, 177
1,1
a(2)=4 since 3*prime(4)+prime(5)-3= 3*7 + 11 - 3 = 29 is prime.
nonn
Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Nov 18 2004
Corrected and extended by Rick L. Shepherd (rshepherd2(AT)hotmail.com), Nov 24 2004
approved