2,1

Let k be an n-digit positive integer, compute all integers that can be formed by combining the digits of k using + - x / and parentheses (but no digit concatenation, exponentiation, or other operators). Let r(k) be the largest range 1...m present in the output set. Then a(n) is the max of r(k) over all n-digit numbers.

a(3)=10 because 1...10 can be made from the digits of 124 ( 1=4-2-1, 2=4-(2/1), 3=4-2+1, 4=4/(2-1), 5=4+2-1, 6=4+(2/1), 7=4+2+1, 8=4*2/1, 9=4*2+1, 10=(4+1)*2 ) and no 3-digit number gives a larger range.

Sequence in context: A088142 A049370 A009343 this_sequence A020132 A013201 A052446

Adjacent sequences: A048172 A048173 A048174 this_sequence A048176 A048177 A048178

nonn,base,more

Mike Keith (domnei(AT)aol.com)