OFFSET
1,2
COMMENTS
This sequence is a variant of A285487.
This sequence is likely a permutation of the natural numbers.
LINKS
Rémy Sigrist, Table of n, a(n) for n = 1..25000
Rémy Sigrist, Scatterplot of the first 25000 terms
Rémy Sigrist, PARI program for A306864
FORMULA
A287170(a(n) * a(n+1)) >= 4.
EXAMPLE
The first terms, alongside the corresponding runs, are:
n a(n) runs in a(n)*a(n+1)
--- ---- -------------------
1 1 2, 5, 11, 17
2 1870 2, 5, 11, 17
3 2 2, 5, 11, 17
4 935 2, 5, 11, 17
5 4 2, 5, 11, 19
6 1045 2, 5, 11, 19
7 8 2, 5, 13, 19
8 1235 2, 5, 13, 19
9 10 2, 5, 11, 17
10 187 2, 5, 11, 17
11 20 2, 5, 11, 19
12 209 2, 5, 11, 19
...
32 91 3, 7, 13, 19
33 57 2-3, 7, 13, 19
34 182 2, 7, 13, 19
...
662 1222 2, 7, 13, 47
663 448 2, 7, 17, 73
664 1241 2-3, 7-11, 17, 73
665 462 2-3, 7-11, 29, 43
666 1247 3, 17, 29, 43
...
PROG
(PARI) See Links section.
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Rémy Sigrist, Mar 14 2019
STATUS
approved