A309574 n-th prime minus its ternary (base 3) reversal.
0, 2, -2, 2, -8, 0, -8, 8, 0, -26, -6, 6, -26, -6, -14, -26, -6, 14, 26, -6, 38, 26, -80, -128, -48, -80, -24, -128, 24, -80, 24, -80, -32, 24, -56, 0, 24, 80, -24, 0, -48, 80, 24, 80, -24, 104, 80, 80, 48, 104, 0, 24, 80, -398, -338, -278, -434, 18, -138
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
- Samuel M. A. Luque, C++ Program (.cpp file) to generate this sequence in whichever m-th base you choose.
- Samuel M. A. Luque, Scatter plot of a(n) up to n = 8132 (primes up to 50 000).
Programs
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Maple
a:= n-> (p-> p-(l->add(l[-i]*3^(i-1), i=1..nops(l)) )(convert(p, base, 3)))(ithprime(n)): seq(a(n), n=1..61); # Alois P. Heinz, Aug 08 2019 -
Mathematica
(# - IntegerReverse[#,3]) &@ Prime@ Range@ 60 (* Giovanni Resta, Aug 09 2019 *)
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PARI
a(n) = my(p=prime(n)); p - fromdigits(Vecrev(digits(p, 3)), 3); \\ Michel Marcus, Aug 09 2019
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Python
from sympy import primerange def rev(n, b): m = 0 while n > 0: m, n = m*b+n%b, n//b return m n, aa = 1, 1 while n <20: if aa in primerange(1,200): print(n, aa-rev(aa, 3)) n = n+1 aa = aa+1 # A.H.M. Smeets, Aug 09 2019
Comments