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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 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.)