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Search: a131715 -id:a131715
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Period 10: repeat [8,6,0,4,2,2,4,0,6,8].
+10
1
8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8, 8, 6, 0, 4, 2, 2, 4, 0, 6, 8
OFFSET
0,1
COMMENTS
See A131715.
FORMULA
a(n) = A155110(n) mod 10.
G.f.: 2*(4*x^8-x^7+x^6+x^5+x^3+x^2-x+4)/((1-x)*(x^4-x^3+x^2-x+1)*(x^4+x^3+x^2+x+1)). - R. J. Mathar, Feb 23 2009
a(n) = (15*(4-m^4+8*m^3-19*m^2+12*m)-2*(m^3-6*m^2+17*m-18)*(-1)^floor(n/5))/12 where m = n-5*floor(n/5). - Luce ETIENNE, Oct 13 2017
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Paul Curtz, Feb 09 2009
EXTENSIONS
Edited by R. J. Mathar, Feb 23 2009
More terms from Jinyuan Wang, Feb 26 2020
STATUS
approved
First differences of A131711.
+10
0
1, 1, 3, -3, 7, -9, 9, -1, -3, 3, -7, -1, 1, 1, 3, -3, 7, -9, 9, -1, -3, 3, -7, -1, 1, 1, 3, -3, 7, -9, 9, -1, -3, 3, -7, -1, 1, 1, 3, -3, 7, -9, 9, -1, -3, 3, -7, -1
OFFSET
0,3
COMMENTS
The equivalent operation on A001333 yields last digits A131707 and their first differences A131715.
FORMULA
a(n) = a(n-12).
From Chai Wah Wu, Jan 09 2021: (Start)
a(n) = - a(n-1) - a(n-4) - a(n-5) - a(n-8) - a(n-9) for n > 8.
G.f.: (x^8 + 8*x^7 + 4*x^6 + 5*x^4 + 4*x^2 + 2*x + 1)/(x^9 + x^8 + x^5 + x^4 + x + 1). (End)
MATHEMATICA
Differences[PadRight[{}, 120, {0, 1, 2, 5, 2, 9, 0, 9, 8, 5, 8, 1}]] (* Harvey P. Dale, Dec 29 2014 *)
CROSSREFS
Cf. A131711.
KEYWORD
sign
AUTHOR
Paul Curtz, Sep 23 2007
EXTENSIONS
Edited by R. J. Mathar, Jul 07 2008
STATUS
approved

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