The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A100402 Digital root of 4^n. 9
 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7, 1, 4, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Equals A141725 mod 9. - Paul Curtz, Sep 15 2008 Sequence is the digital root of A016777. - Odimar Fabeny, Sep 13 2010 Digital root of the powers of any number congruent to 4 mod 9. - Alonso del Arte, Jan 26 2014 Period 3: repeat [1, 4, 7]. - Wesley Ivan Hurt, Aug 26 2014 REFERENCES Cecil Balmond, Number 9: The Search for the Sigma Code. Munich, New York: Prestel (1998): 203. LINKS Index entries for linear recurrences with constant coefficients, signature (0, 0, 1). FORMULA a(n) = 4^n mod 9. - Zerinvary Lajos, Nov 25 2009 From R. J. Mathar, Apr 13 2010: (Start) a(n) = a(n-3) for n>2. G.f.: (1+4*x+7*x^2)/ ((1-x)*(1+x+x^2)). (End) a(n) = A010888(A000302(n)). - Michel Marcus, Aug 25 2014 a(n) = 3*A010872(n) + 1. - Robert Israel, Aug 25 2014 a(n) = 4 - 3*cos(2*n*Pi/3) - sqrt(3)*sin(2*n*Pi/3). - Wesley Ivan Hurt, Jun 30 2016 EXAMPLE 4^2 = 16, digitalroot(16) = 7, the third entry. MAPLE A100402:=n->4^n mod 9: seq(A100402(n), n=0..100); # Wesley Ivan Hurt, Aug 26 2014 MATHEMATICA Table[Mod[4^n, 9], {n, 0, 99}] (* Alonso del Arte, Jan 26 2014 *) PROG (Sage) [power_mod(4, n, 9)for n in range(0, 105)] # Zerinvary Lajos, Nov 25 2009 (MAGMA) [4^n mod 9 : n in [0..100]]; // Wesley Ivan Hurt, Aug 26 2014 (PARI) a(n)=[1, 4, 7][1+n%3]; \\ Joerg Arndt, Aug 26 2014 CROSSREFS Cf. Digital roots of powers of c mod 9: c = 2, A153130; c = 5, A070366; c = 7, A070403; c = 8, A010689. Cf. A000302, A010872, A010888, A141725, A016777. Sequence in context: A123734 A011519 A131594 * A135004 A086234 A016490 Adjacent sequences:  A100399 A100400 A100401 * A100403 A100404 A100405 KEYWORD easy,nonn,base AUTHOR Cino Hilliard, Dec 31 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 30 20:55 EST 2020. Contains 338812 sequences. (Running on oeis4.)