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 A247253 First differences of A251239. 11
 1, 6, 6, 7, 1, 7, 13, 8, 10, 1, 17, 8, 1, 13, 13, 13, 5, 10, 11, 5, 9, 8, 19, 10, 11, 7, 11, 5, 9, 27, 9, 13, 5, 23, 5, 9, 17, 9, 11, 11, 7, 21, 9, 7, 5, 17, 27, 11, 7, 9, 17, 5, 13, 9, 21, 11, 7, 13, 9, 9, 17, 31, 7, 7, 9, 29, 9, 25, 5, 7, 13, 15, 15, 11 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) = A251239(n+1) - A251239(n); Conjecture 1: a(n) > 0, since presumably primes occur in A098550 in natural order; Conjecture 2: it seems that a(n) = 1 only for n = 1, 5, 10 and 13; Conjecture 3: a(n) - 1 = number of composite terms between prime(n) and prime(n+1) in A098550; Conjecture 4: a(n) = A251417(n+5) for n>7. (The first four conjectures are due to Reinhard Zumkeller.) Conjecture 5: Apart from first term, this is equal to the sequence of run lengths in A251549. These run lengths begin 2, 6, 6, 7, 1, 7, 13, 8, 10, 1, 17, 8, 1, 13, 13, 13, 5, 10, 11, 5, 9, ... . - N. J. A. Sloane, Dec 18 2014 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 PROG (Haskell) a247253 n = a247253_list !! (n-1) a247253_list = zipWith (-) (tail a251239_list) a251239_list CROSSREFS Cf. A251239, A098550, A002808, A251417, A251549. Sequence in context: A082796 A078245 A241057 * A244293 A196737 A070058 Adjacent sequences:  A247250 A247251 A247252 * A247254 A247255 A247256 KEYWORD nonn AUTHOR Reinhard Zumkeller, Dec 02 2014 STATUS approved

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Last modified April 1 10:33 EDT 2020. Contains 333159 sequences. (Running on oeis4.)