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A145011 First differences of A007775. 3

%I

%S 6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,

%T 2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,

%U 2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2,6,4,2,4,2,4,6,2

%N First differences of A007775.

%C Terms of the simple continued fraction of 3836/[sqrt(19822530)-3836]. - _Paolo P. Lava_, Aug 05 2009

%C Also the first differences of A084968 divided by 7. - _Antti Karttunen_, May 01 2015

%H Reinhard Zumkeller, <a href="/A145011/b145011.txt">Table of n, a(n) for n = 1..10000</a>

%F Period 8: repeat 6,4,2,4,2,4,6,2.

%F a(n) = (1/112)*{-41*(n mod 8)+71*[(n+1) mod 8]-13*[(n+2) mod 8]-13*[(n+3) mod 8]+43*[(n+4) mod 8]-13*[(n+5) mod 8]+43*[(n+6) mod 8]+43*[(n+7) mod 8]}, with n>=0. [_Paolo P. Lava_, Aug 28 2009]

%F a(n) = 2*((abs(abs((n mod 8) - 3) - 1) mod 3) + 1). - _Pieter Stadhouders_, Mar 09 2010

%t Differences[Select[Range[400],GCD[#,30]==1&]] (* _Harvey P. Dale_, Dec 07 2011 *)

%o (Haskell)

%o a145011 n = a145011_list !! (n-1)

%o a145011_list = zipWith (-) (tail a007775_list) a007775_list

%o -- _Reinhard Zumkeller_, Jan 06 2013

%o (PARI) a(n)=[4,6,4,2,4,2][n%8+1] \\ _Charles R Greathouse IV_, Oct 20 2013

%Y Cf. A007775, A084968.

%Y Multiplied by 7: row 4 of A257251.

%K nonn,easy

%O 1,1

%A _Ki Punches_, Feb 25 2009

%E Edited by _Omar E. Pol_, Mar 02 2009

%E Offset corrected by _Reinhard Zumkeller_, Jan 06 2013

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Last modified July 28 12:39 EDT 2017. Contains 289889 sequences.