A229686 The negative number of minimum absolute value not obtainable from 1 in n steps using addition, multiplication, and subtraction.

-1, -2, -4, -9, -29, -85, -311, -1549, -9851, -74587, -956633

Offset

0,2

Comments

This is similar to A141414 but applied to negative numbers. It is the greatest negative number that requires an n step SLP (Stright Line Program) to compute it.

Links

Table of n, a(n) for n=0..10.

Example

For n=1 the value is -1 since -1 requires 2 steps SLP: 1,2,-1.
For n=2 the value is -2 since -2 requires 3 steps SLP: 1,2,3,-2.
For n=3 the value is -4 since -3 also requires only 3 steps but -4 requires 4: 1,2,4,5,-4.

Crossrefs

Cf. A141414, A216999, A214872.

Sequence in context: A241404 A005095 A300491 * A208965 A306505 A243789

Adjacent sequences: A229683 A229684 A229685 * A229687 A229688 A229689

Keyword

sign,hard

Author

Gil Dogon, Sep 27 2013

Status

approved