A138339 Smallest index in A138343 which starts a plateau of n consecutive integers.

0, 7, 4, 12

Offset: 1

Author

Artur Jasinski, Mar 16 2008

Keywords

• nonn
• less
• base
• bref

Comments

The sequence provides an indication of regions of nearly no improvements of the sequence of convergents to Pi when measured by the count of correct digits after rounding. A "plateau" of n consecutive integers is defined by a(n) = j such that A138343(j) = A138343(j+n-1) and such that none of the intermediate A138343 with index j+1 up to j+n-2 drop below this level.

Examples

			a(3)=4 because the A138343(4) to A138343(6) are the earliest plateau of length 3.
The fact that there is a local maximum at A138343(5)=9 above the plateau is consistent with the definition.
		

Crossrefs

Cf. A138335, A138336, A138337, A138343.

Extensions

Definition and values adapted to redefined A138343 - R. J. Mathar, Oct 01 2009