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A165669 First digit of the decimal expansion of (n^2+2)/7 after the decimal point. 0
2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4, 2, 4, 8, 5, 5, 8, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Periodic with period length 7.

LINKS

Table of n, a(n) for n=0..104.

FORMULA

a(n) = floor(10*(n^2+2)/7) mod 10. [R. J. Mathar, Sep 23 2009]

a(n)=(1/49)*{26*(n mod 7)+40*[(n+1) mod 7]-9*[(n+2) mod 7]+12*[(n+3) mod 7]+33*[(n+4) mod 7]-16*[(n+5) mod 7]-2*[(n+6) mod 7]}, with n>=0 [From Paolo P. Lava, Nov 12 2009]

EXAMPLE

For n=0, (0^2+2)/7=0.285.... and 2 is the first digit after the point.

For n=1, (1^2+2)/7=0.4285..., and 4 is the first digit after the point.

MATHEMATICA

Table[Mod[Floor[10*N[(n^2+2)/7]], 10], {n, 0, 110}] (* Harvey P. Dale, Jul 05 2015 *)

CROSSREFS

Cf. A165664.

Sequence in context: A163339 A092892 A146079 * A227818 A300890 A021893

Adjacent sequences:  A165666 A165667 A165668 * A165670 A165671 A165672

KEYWORD

nonn,base,easy,less

AUTHOR

Vincenzo Librandi, Sep 24 2009

EXTENSIONS

Edited by R. J. Mathar, Sep 26 2009

STATUS

approved

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Last modified September 29 04:42 EDT 2020. Contains 337420 sequences. (Running on oeis4.)