A304431 a(n+1) = 1 + min( 2*a(floor(n/2)), 3*a(floor(n/3)) ), with a(0) = 0.

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, 13, 13, 13, 13, 13, 13, 13, 13, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 21, 21, 22, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27

Offset: 0

Author

Michael Somos, May 12 2018

Keywords

• nonn

Comments

Same recursion as Knuth numbers A007448 but different initial value.

Crossrefs

Cf. A007448.

Programs

PARI

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