A339580 Indices of records in A339579.

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

Offset

1,2

Comments

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

a(11) <= 90616211958465842220.

References

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

Links

Table of n, a(n) for n=1..10.

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.

Formula

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

Example

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

Crossrefs

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

Sequence in context: A053996 A218143 A203477 * A374392 A115704 A066751

Adjacent sequences: A339577 A339578 A339579 * A339581 A339582 A339583

Keyword

nonn,more

Author

N. J. A. Sloane, 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

Status

approved