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Tribonacci representation of primes, written in base 10.
2

%I #18 Jun 12 2018 21:13:32

%S 2,3,5,8,12,16,20,22,27,37,40,48,52,54,67,74,82,84,91,99,101,108,130,

%T 137,147,152,154,162,164,169,194,198,205,209,256,258,265,273,277,288,

%U 294,297,309,320,324,326,341,358,363,365,387,394,396,409,419,426,434,436,515,520,522,534,554,560

%N Tribonacci representation of primes, written in base 10.

%H Robert Israel, <a href="/A305377/b305377.txt">Table of n, a(n) for n = 1..10001</a>

%p L[0]:= [0]: L[1]:= [1]:

%p for d from 2 to 15 do

%p L[d]:= map(t -> (2*t, `if`(t mod 4 <> 3, 2*t+1,NULL)), L[d-1])

%p od:

%p A003726:=map(op,[seq(L[i],i=0..15)]):

%p seq(A003726[ithprime(i)+1],i=1..numtheory:-pi(nops(A003726)-1)); # _Robert Israel_, Jun 12 2018

%o (Python)

%o from sympy import prime

%o def A305377(n):

%o m, tlist, s = prime(n), [1,2,4], 0

%o while tlist[-1]+tlist[-2]+tlist[-3] <= m:

%o tlist.append(tlist[-1]+tlist[-2]+tlist[-3])

%o for d in tlist[::-1]:

%o s *= 2

%o if d <= m:

%o s += 1

%o m -= d

%o return s # _Chai Wah Wu_, Jun 12 2018

%Y Equals A003726(prime(n)).

%Y Cf. A278038, A305379.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Jun 12 2018

%E More terms from _Robert Israel_, Jun 12 2018