OFFSET
1,1
COMMENTS
a(n) is the rank of prime(n) in the base-9 dominance order on the natural numbers.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Tyler Ball and Daniel Juda, Dominance over N, Rose-Hulman Undergraduate Mathematics Journal, Vol. 13, No. 2, Fall 2013.
EXAMPLE
The fifth prime is 11, 11 in base 9 is (1,2) so a(5)=1+2=3.
MATHEMATICA
Table[Plus @@ IntegerDigits[Prime[n], 9], {n, 1, 100}] (* Vincenzo Librandi, Mar 25 2014 *)
PROG
(Sage) [sum(i.digits(base=9)) for i in primes_first_n(200)]
(Magma) [&+Intseq(NthPrime(n), 9): n in [1..100]]; // Vincenzo Librandi, Mar 25 2014
(PARI) a(n) = sumdigits(prime(n), 9); \\ Michel Marcus, Mar 04 2023
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Tom Edgar, Mar 24 2014
STATUS
approved