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a(n) = smallest integer >= n which has only prime factors 3 and 5.
2

%I #4 Mar 30 2012 16:51:07

%S 1,3,3,5,5,9,9,9,9,15,15,15,15,15,15,25,25,25,25,25,25,25,25,25,25,27,

%T 27,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,45,75,75,75,75,

%U 75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75,75

%N a(n) = smallest integer >= n which has only prime factors 3 and 5.

%o (R) f <- function(n) nextn(n, factors = c(3,5))

%o a <- matrix(1:256,ncol=1)

%o apply(a,1,f)

%Y Cf. A130916, A134361, A151969.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Aug 23 2009; corrected Mar 07 2012