A383143
Number of positive integers with a shortest addition-subtraction chain of length n.
Original entry on oeis.org
1, 1, 2, 3, 5, 9, 16, 28, 49, 88, 156, 280, 499, 904, 1639, 2986, 5442, 9936, 18134
Offset: 0
a(6) = 16 because the number of occurrences of 6 in A128998 is 16. These numbers are 19, 21, 22, 23, 25, 26, 27, 28, 30, 31, 33, 34, 36, 40, 48, 64.
A383336
Smallest number with shortest addition-multiplication-exponentiation chain of length n.
Original entry on oeis.org
1, 2, 3, 5, 7, 13, 23, 79, 214, 1418, 5991
Offset: 0
a(7) = 79 because all smaller numbers have addition-multiplication-exponentiation chains of length at most 6, but the shortest chain for 79 has length 7. One such chain is (1, 2, 3, 5, 32, 37, 42, 79). (There are also such chains that do not use exponentiation, such as (1, 2, 3, 4, 5, 15, 75, 79).)
Showing 1-2 of 2 results.
Comments