A137807 Final digit of prime(n)^2.

4, 9, 5, 9, 1, 9, 9, 1, 9, 1, 1, 9, 1, 9, 9, 9, 1, 1, 9, 1, 9, 1, 9, 1, 9, 1, 9, 9, 1, 9, 9, 1, 9, 1, 1, 1, 9, 9, 9, 9, 1, 1, 1, 9, 9, 1, 1, 9, 9, 1, 9, 1, 1, 1, 9, 9, 1, 1, 9, 1, 9, 9, 9, 1, 9, 9, 1, 9, 9, 1, 9, 1, 9, 9, 1, 9, 1, 9, 1, 1, 1, 1, 1, 9, 1, 9, 1, 9, 1, 9, 9, 1, 9, 1, 1, 9, 1, 1, 9, 1, 9, 9, 9, 1, 1

Offset: 1

Author

Paul Curtz, Apr 29 2008

Keywords

• nonn
• base

Comments

Euler and Sadek ask whether the sequence, interpreted as the decimal expansion N = 0.49591..., is rational or irrational. - Charles R Greathouse IV, Apr 19 2010

References

• R. Euler and J. Sadek, A number that gives the unit digit of n^n. Journal of Recreational Mathematics, 29:3 (1998), pp. 203-204. [From Charles R Greathouse IV, Apr 19 2010]

Programs

Maple

A001248 := proc(n) ithprime(n)^2 ; end: A010879 := proc(n) n mod 10 ; end: A137807 := proc(n) A010879(A001248(n)) ; end: seq(A137807(n),n=1..140) ; # R. J. Mathar, May 03 2008

Mathematica

Mod[Prime[Range[110]]^2,10] (* Harvey P. Dale, Jan 20 2022 *)

Formula

a(n) = A010879(A001248(n)). - R. J. Mathar, May 03 2008

Extensions

More terms from R. J. Mathar, May 03 2008