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 A084336 a(n) is the smallest composite number not already in the sequence such that the absolute values of the successive differences are distinct primes. 0
 4, 6, 9, 14, 21, 8, 25, 36, 55, 12, 35, 64, 27, 58, 99, 10, 57, 110, 39, 98, 15, 76, 143, 16, 95, 22, 119, 18, 121, 228, 49, 158, 45, 176, 315, 32, 169, 20, 171, 328, 51, 214, 33, 200, 391, 24, 217, 44, 243, 46, 273, 34, 245, 468, 85, 314, 63, 296, 537, 28, 285, 548, 69 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS The absolute values of the successive difference are 2, 3, 5, 7, 13, 17, 11, 19, 43, 23, 29, 37, 31, ... Does every composite number occur in the sequence? Does every prime occur as a difference? LINKS Table of n, a(n) for n=0..62. MATHEMATICA a[0]=4; a[n_] := a[n]=Module[{x, d}, For[x=6, True, x++, If[ !PrimeQ[x]&&PrimeQ[d=Abs[x-a[n-1]]]&&!MemberQ[a/@Range[n-1], x]&&!MemberQ[Table[Abs[a[i+1]-a[i]], {i, 0, n-2}], d], Return[x]]]] CROSSREFS Sequence in context: A310673 A171664 A286303 * A094750 A241013 A330071 Adjacent sequences: A084333 A084334 A084335 * A084337 A084338 A084339 KEYWORD nonn AUTHOR Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 18 2003 EXTENSIONS Edited by Dean Hickerson, Jun 30 2003 STATUS approved

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Last modified September 28 16:15 EDT 2023. Contains 365736 sequences. (Running on oeis4.)