

A239693


Base 7 sum of digits of prime(n).


3



2, 3, 5, 1, 5, 7, 5, 7, 5, 5, 7, 7, 11, 7, 11, 5, 5, 7, 7, 5, 7, 7, 11, 11, 13, 5, 7, 5, 7, 5, 7, 11, 11, 13, 5, 7, 7, 7, 11, 11, 11, 13, 11, 13, 5, 7, 7, 13, 11, 13, 11, 11, 13, 11, 11, 11, 11, 13, 13, 11, 13, 17, 13, 11, 13, 11, 13, 13, 5, 7, 5, 5, 7, 7
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OFFSET

1,1


COMMENTS

a(n) is the rank of prime(n) in the base7 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, RoseHulman Undergraduate Mathematics Journal, Vol. 13, No. 2, Fall 2013.


FORMULA

a(n) = A053828(A000040(n)).


EXAMPLE

The fifth prime is 11, 11 in base 7 is (1,4) so a(5)=1+4=5.


MATHEMATICA

Table[Plus @@ IntegerDigits[Prime[n], 7], {n, 1, 100}] (* Vincenzo Librandi, Mar 25 2014 *)


PROG

(Sage) [sum(i.digits(base=7)) for i in primes_first_n(200)]
(MAGMA) [&+Intseq(NthPrime(n), 7): n in [1..100]]; // Vincenzo Librandi, Mar 25 2014


CROSSREFS

Cf. A007605, A014499, A053828, A239690, A239691, A239692.
Sequence in context: A123217 A039704 A002752 * A256655 A128047 A105870
Adjacent sequences: A239690 A239691 A239692 * A239694 A239695 A239696


KEYWORD

nonn,base


AUTHOR

Tom Edgar, Mar 24 2014


STATUS

approved



