OFFSET
1,1
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
Eric Weisstein's World of Mathematics, Pierpont Prime
FORMULA
MATHEMATICA
smooth3Q[n_] := n == 2^IntegerExponent[n, 2]*3^IntegerExponent[n, 3];
a[n_] := Boole[PrimeQ[n] && smooth3Q[n - 1]];
Table[a[n], {n, 1, 100}] (* Jean-François Alcover, Oct 16 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Aug 29 2006
STATUS
approved