A383142 Smallest positive integer with shortest addition-subtraction chain of length n.

1, 2, 3, 5, 7, 11, 19, 29, 53, 87, 151, 267, 461, 811, 1383, 2357, 4277, 7499, 14003, 25931, 44269, 87773, 152947, 271563

Offset

0,2

Links

Table of n, a(n) for n=0..23.

Neill Clift, Addition Subtraction Chains.

Index to sequences related to the complexity of n

Formula

a(n) >= A003064(n).

Example

a(8) = 53 because 53 is the smallest positive integer k such that A128998(k) = 8. An example of a shortest addition-subtraction chain for 53 is (1 2 3 4 7 14 25 28 53). a(8) > A003064(8) because an optimal chain for A003064(8) = 47 has length 7: (1 2 3 6 12 24 23 47).

Crossrefs

Cf. A003064, A128998, A383001, A383143.

Sequence in context: A003064 A057429 A137814 * A065726 A215161 A227907

Adjacent sequences: A383139 A383140 A383141 * A383143 A383144 A383145

Keyword

nonn,hard,more

Author

Jinyuan Wang, Apr 17 2025

Status

approved