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a(n+1) = 1 + min( 2*a(floor(n/2)), 3*a(floor(n/3)) ), with a(0) = 0.
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%I #4 May 12 2018 17:21:38

%S 0,1,1,1,3,3,3,3,3,4,4,4,4,7,7,7,7,7,7,9,9,9,9,9,9,9,9,10,13,13,13,13,

%T 13,13,13,13,13,13,13,13,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,

%U 21,21,22,27,27,27,27,27,27,27,27,27,27,27,27,27,27

%N a(n+1) = 1 + min( 2*a(floor(n/2)), 3*a(floor(n/3)) ), with a(0) = 0.

%C Same recursion as Knuth numbers A007448 but different initial value.

%o (PARI) {a(n) = if( n<1, 0, n--; 1 + min( a(n\2)*2, a(n\3)*3 ))};

%Y Cf. A007448.

%K nonn

%O 0,5

%A _Michael Somos_, May 12 2018