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 A174857 The minimum distance k>0 such that A020639(n+k)=A020639(n). 4
 2, 6, 2, 20, 2, 42, 2, 6, 2, 110, 2, 156, 2, 6, 2, 272, 2, 342, 2, 6, 2, 506, 2, 10, 2, 6, 2, 812, 2, 930, 2, 6, 2, 20, 2, 1332, 2, 6, 2, 1640, 2, 1806, 2, 6, 2, 2162, 2, 28, 2, 6, 2, 2756, 2, 10, 2, 6, 2, 3422, 2, 3660, 2, 6, 2, 20, 2, 4422, 2, 6, 2, 4970, 2, 5256, 2, 6, 2, 14, 2, 6162 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS The sequence has the same records as A002618. LINKS FORMULA If n is even, then a(n)=2. If n=3k and A020639(k)>=3, then a(n)=6. If n is prime, then a(n)=A036689(n). MAPLE A174857 := proc(n) local k, aref ; aref := A020639(n) ; for k from 1 do if A020639(n+k) = aref then return k; end if; end do: end proc: seq(A174857(n), n=2..80) ; # R. J. Mathar, Dec 07 2010 CROSSREFS Cf. A020639, A002618, A036689 Sequence in context: A122663 A100892 A126287 * A008556 A096485 A125032 Adjacent sequences:  A174854 A174855 A174856 * A174858 A174859 A174860 KEYWORD nonn AUTHOR Vladimir Shevelev, Mar 31 2010 STATUS approved

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