A084336 - OEIS

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.

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

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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