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 A199714 A puzzle - explanation is not known. 2
 0, 9, 23, 30, 35, 49, 58, 73, 94 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS In November 1987, an editor at the Astrophysical Journal wrote to N. J. A. Sloane with three sequences whose explanation was not known to her. She said: "As to the pedigree of these sequences, not much is known. But they are US in origin, and /not/ Hungarian".  One of the three was the number-theoretical sequence A007468. The other two are now A199714 and A199715. Looking at the first differences (9, 14, 7, 5, 14, 9, 15, 21), one may notice that the last three terms are 3*(3, 5, 7), and the relation 9 = 14 - 5 seems to appear twice. Taking the second differences yields (5, -7, -2, 9, -5, 6, 6), where similar relations 5 - 7 = -2 and 7 + 2 = 9 can be seen.  - M. F. Hasler, Mar 14 2018 LINKS CROSSREFS Sequence in context: A165484 A009235 A031023 * A054302 A147395 A302906 Adjacent sequences:  A199711 A199712 A199713 * A199715 A199716 A199717 KEYWORD nonn,unkn AUTHOR N. J. A. Sloane, Nov 09 2011 STATUS approved

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Last modified June 17 22:14 EDT 2021. Contains 345086 sequences. (Running on oeis4.)