A355015 The least integer with cost n, using the cost function used in sequence A354914.

1, 2, 3, 7, 23, 719, 1169951

Offset: 0

Author

Stan Wagon, Joseph DeVincentis, and Al Zimmermann, Jun 15 2022

Keywords

• nonn
• hard
• more

Comments

The values up to 1169951 were computed by Joseph DeVincentis, Stan Wagon, and Al Zimmermann. The values appear to rise roughly quadratically, so the next one might be near 10^12 and impossible to find. It is known that the sequence is infinite: that is, the cost function is not bounded.

Examples

			Example: a(4) = 23 because 23 can be reached by the path 1, 2, 3, 4, 5, 20, 23, which has 4 addition steps, and one can check that each smaller number has cost at most 3.
		

Crossrefs

Cf. A354914.

Extensions

a(6) corrected by Stan Wagon, Feb 15 2023