A165664 First digit of the decimal expansion of (n^2-2)/7 after the decimal point.

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

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]

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 A337615

Adjacent sequences: A165661 A165662 A165663 * A165665 A165666 A165667

Keyword

nonn,base,less

Author

Vincenzo Librandi, Sep 24 2009

Status

approved