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 A344659 Lexicographically earliest sequence of distinct nonnegative terms on a square spiral such that each term forms no prime value in the eight sums when each term is added to each of its eight nearest neighbors. 4
 0, 1, 8, 14, 4, 6, 9, 15, 20, 5, 7, 13, 2, 12, 10, 11, 16, 22, 18, 3, 17, 19, 25, 29, 28, 21, 23, 27, 31, 26, 24, 30, 32, 34, 35, 33, 36, 41, 40, 42, 39, 37, 38, 43, 45, 47, 49, 53, 57, 48, 51, 54, 61, 50, 44, 46, 52, 56, 58, 60, 59, 65, 55, 62, 63, 70, 64, 74, 66, 69, 67, 68, 72, 73, 77, 71, 75 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS . 36--33--35--34--32--30--24 | | 41 16--11--10--12---2 26 | | | | 40 22 4--14---8 13 31 | | | | | | 42 18 6 0---1 7 27 | | | | | 39 3 9--15--20---5 23 . | | | . 37 17--19--25--29--28--21 . | | 38--43--45--47--49--53--57--48 . LINKS Table of n, a(n) for n=1..77. EXAMPLE The eight terms that are in contact with the initial zero are 1, 8, 14, 4, 6, 9, 15, 20: none of them is prime [forcing the sum a(k) + 0 to be nonprime, with k<9]; more generally, no term of the square spiral when added to any of its eight nearest neighbors sums to a prime. CROSSREFS Cf. A063826, A344660, A002808, A000040. Sequence in context: A228799 A329499 A220393 * A109847 A260059 A122459 Adjacent sequences: A344656 A344657 A344658 * A344660 A344661 A344662 KEYWORD nonn AUTHOR Eric Angelini and Scott R. Shannon, May 26 2021 STATUS approved

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Last modified May 30 20:23 EDT 2023. Contains 363061 sequences. (Running on oeis4.)