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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. 0
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 (list; graph; refs; listen; history; text; internal format)
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: A235117 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

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Last modified June 5 14:36 EDT 2020. Contains 334841 sequences. (Running on oeis4.)