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A165664 First digit of the decimal expansion of (n^2-2)/7 after the decimal point. 1
2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8, 2, 0, 0, 2, 8, 7, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

Periodic with period length 7.

LINKS

Table of n, a(n) for n=2..106.

FORMULA

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

a(n)=(1/49)*{51*(n mod 7)+2*[(n+1) mod 7]+16*[(n+2) mod 7]-33*[(n+3) mod 7]-5*[(n+4) mod 7]+9*[(n+5) mod 7]+23*[(n+6) mod 7]}, with n>=0 [From Paolo P. Lava, Nov 12 2009]

EXAMPLE

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

For n=3, (3^2-2)/7=1.0000.., integer, and the digit is 0.

For n=4, (4^2-2)/7=2.0000, integer and the digit is 0.

For n=5, (5^2-2)/7=3.2857.. and the first decimal after the point is 2.

MATHEMATICA

Table[IntegerPart[10*FractionalPart[N[(n^2-2)/7]]], {n, 2, 110}] (* Harvey P. Dale, Apr 08 2013 *)

CROSSREFS

Sequence in context: A246814 A116597 A202496 * A019263 A244132 A169776

Adjacent sequences:  A165661 A165662 A165663 * A165665 A165666 A165667

KEYWORD

nonn,base,less

AUTHOR

Vincenzo Librandi, Sep 24 2009

STATUS

approved

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Last modified November 18 07:22 EST 2019. Contains 329252 sequences. (Running on oeis4.)