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A255617 a(n) is the smallest even term in A098550 less than 2*prime(n) but occurring after 2*prime(n); a(n)=0 if no such term exists. 2
0, 0, 0, 6, 18, 18, 30, 0, 0, 54, 54, 70, 78, 78, 90, 102, 110, 120, 0, 140, 144, 150, 0, 0, 0, 198, 200, 0, 216, 0, 252, 252, 270, 270, 0, 0, 310, 0, 0, 340, 348, 360, 374, 0, 0, 0, 402, 438, 440, 440, 450, 0, 0, 486, 486, 518, 528, 540, 546, 546, 0, 572, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Conjecture: for n>=5, positive a(n) > prime(n). Together with the known conjecture that, for n>=26, 2*prime(n) is the first multiple of prime(n) appearing in A098550, this conjecture would easily implies that the primes in A098550 occur in the natural order.
(Indeed, if 101<=P<Q, then, as known, the first multiple of P, 2*P, appears earlier than the first multiple of Q, 2*Q. By the conjecture, after 2*P there cannot appear any even number <P; thus if a(n)=2*P, then a(n+2)=P appears before 2*Q.)
LINKS
David L. Applegate, Hans Havermann, Bob Selcoe, Vladimir Shevelev, N. J. A. Sloane, and Reinhard Zumkeller, The Yellowstone Permutation, arXiv preprint arXiv:1501.01669 [math.NT], 2015.
CROSSREFS
Sequence in context: A252897 A174904 A074390 * A253771 A223218 A077630
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, Feb 28 2015
STATUS
approved

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Last modified March 29 00:26 EDT 2024. Contains 371264 sequences. (Running on oeis4.)