A179802 Digital root of A179545.

3, 9, 3, 9, 3, 9, 3, 9, 3, 3, 9, 9, 3, 9, 3, 3, 3, 9, 9, 3, 9, 9, 3, 3, 9, 3, 9, 3, 9, 3, 9, 3, 3, 9, 3, 9, 9, 9, 3, 3, 3, 9, 3, 9, 3, 9, 9, 9, 3, 9, 3, 3, 9, 3, 3, 3, 3, 9, 9, 3, 9, 3, 9, 3, 9, 3, 9, 9, 3, 9, 3, 3, 9, 9, 9, 3, 3, 9, 3, 9, 3, 9, 3, 9, 9, 3, 3

Offset

1,1

Comments

Because every term in A179545 is a multiple of 3, each term of this sequence is 3 or 9. - Nathaniel Johnston, May 04 2011

a(n) = 3 if and only if prime(n) == 2 (mod 3); otherwise a(n) = 9. - Charles R Greathouse IV, May 19 2011

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Formula

a(n) = A010888(A179545(n)). - Michel Marcus, Mar 08 2022

Maple

read("transforms") ; A010888 :=proc(n) local a; a := digsum(n) ; if a > 9 then return procname(a) ; else return a; end if; end proc:
A179545 := proc(n) local p; p := ithprime(n); 3*p*(p-1)/2 ; end proc:
A179802 := proc(n) A010888(A179545(n)) ; end proc:
seq(A179802(n), n=1..180) ; # R. J. Mathar, Oct 03 2010

Prog

(PARI) apply(p->if(p%3==2, 3, 9), primes(10000)) \\ Charles R Greathouse IV, May 19 2011

Crossrefs

Cf. A000040, A010888, A179545.

Sequence in context: A099319 A231828 A268580 * A010707 A097665 A284564

Adjacent sequences: A179799 A179800 A179801 * A179803 A179804 A179805

Keyword

easy,nonn,base

Author

Odimar Fabeny, Jul 27 2010

Extensions

More terms from R. J. Mathar, Oct 03 2010

Status

approved