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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

Table of n, a(n) for n=1..9.

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 October 15 03:09 EDT 2019. Contains 328025 sequences. (Running on oeis4.)