A239695 Base 9 sum of digits of prime(n).
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
Examples
The fifth prime is 11, 11 in base 9 is (1,2) so a(5)=1+2=3.
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.
Programs
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Magma
[&+Intseq(NthPrime(n),9): n in [1..100]]; // Vincenzo Librandi, Mar 25 2014
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Mathematica
Table[Plus @@ IntegerDigits[Prime[n], 9], {n, 1, 100}] (* Vincenzo Librandi, Mar 25 2014 *) -
PARI
a(n) = sumdigits(prime(n), 9); \\ Michel Marcus, Mar 04 2023
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Sage
[sum(i.digits(base=9)) for i in primes_first_n(200)]
Comments