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A239695
Base 9 sum of digits of prime(n).
1
2, 3, 5, 7, 3, 5, 9, 3, 7, 5, 7, 5, 9, 11, 7, 13, 11, 13, 11, 15, 9, 15, 3, 9, 9, 5, 7, 11, 5, 9, 7, 11, 9, 11, 13, 15, 13, 3, 7, 5, 11, 5, 7, 9, 13, 7, 11, 15, 11, 13, 17, 15, 17, 11, 9, 7, 13, 7, 13, 9, 11, 13, 11, 15, 17, 13, 11, 9, 11, 13, 9, 15, 15, 13, 11
OFFSET
1,1
COMMENTS
a(n) is the rank of prime(n) in the base-9 dominance order on the natural numbers.
LINKS
Tyler Ball and Daniel Juda, Dominance over N, Rose-Hulman Undergraduate Mathematics Journal, Vol. 13, No. 2, Fall 2013.
FORMULA
a(n) = A053830(A000040(n)).
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
KEYWORD
nonn,base
AUTHOR
Tom Edgar, Mar 24 2014
STATUS
approved