A339580 Indices of records in A339579.

1, 3, 90, 1122660, 19099920, 85864770, 26089808580, 554688278430, 4090932431513070, 95405042230542330

Offset: 1

Author

N. J. A. Sloane, Dec 24 2020

Keywords

• nonn
• more

Comments

The records themselves begin 4,5,6,7,8,9,10,12,13,14.

a(11) <= 90616211958465842220.

Examples

			90 is in the sequence as A339579(90) = 6 (90*2^k - 1 is prime for k = 0..5 and composite for k = 6) and A339579(m) < 6 for m < 90. - _David A. Corneth_, Dec 24 2020
		

References

• Carl Pomerance, Problem 81:21 (= 321), in R. K. Guy problem list.

Links

• R. K. Guy, editor, Western Number Theory Problems, 1985-12-21 & 23, Typescript, Jul 13 1986, Dept. of Math. and Stat., Univ. Calgary, 11 pages. Annotated scan of pages 1, 3, 7, 9, with permission.

Crossrefs

Cf. A063377, A124514, A125113, A339579, A339581.

Formula

a(n) = A339581(n) + 1 for n >= 2. - David A. Corneth, Dec 24 2020

Extensions

a(8)-a(10) were taken from A057331 and the bound on a(11) was taken from A005602. - David A. Corneth and Amiram Eldar, Dec 25 2020