A247270 Let k == 1 or 5 (mod 6) (A007310). a(n) is the greatest number of the initial values of k such that k^2+6*n-4 divided by the maximal possible power of 3 takes only prime values or 1.

6, 10, 6, 8, 2, 7, 6, 3, 1, 2, 4, 5, 0, 1, 4, 15, 2, 0, 3, 2, 1, 9, 3, 1, 0, 3, 17, 0, 1, 2, 2, 4, 0, 1, 1, 7, 5, 0, 0, 2, 3, 1, 0, 1, 2, 0, 3, 0, 1, 2, 6, 2, 0, 1, 2, 1, 1, 0, 1, 0, 0, 7, 0, 2, 2, 2, 0, 1, 1, 1, 25, 0, 0, 0, 2, 5, 1, 0, 1, 2, 0, 3, 0, 1, 0, 2

Offset

1,1

Comments

In the first 2*10^7 terms the numbers 15, 16, 17 and 25 appear only once. Here is the distribution:

0 16206595

1 3157812

2 547566

3 71442

4 12617

5 2848

6 817

7 211

8 53

9 20

10 11

11 2

12 2

13 0

14 0

15 1

16 1

17 1

18 0

19 0

20 0

21 0

22 0

23 0

24 0

25 1

Links

Table of n, a(n) for n=1..86.

Example

For n=1, we have 1,1,17,41,19,97,121. So a(1)=6.

Crossrefs

Sequence in context: A339590 A074288 A156383 * A010726 A084365 A066135

Adjacent sequences: A247267 A247268 A247269 * A247271 A247272 A247273

Keyword

nonn

Author

Vladimir Shevelev and Peter J. C. Moses, Sep 11 2014

Status

approved