A134069 Primes in A038399.

11, 211, 853211

Offset: 1

Author

Alexander Adamchuk, Oct 06 2007

Keywords

• bref
• hard
• more
• nonn
• base

Comments

A038399 = {1, 11, 211, 3211, 53211, 853211, 13853211, 2113853211, ...} = concatenation of first n nonzero Fibonacci numbers in reverse order.

From Robert Israel, Sep 14 2016: (Start)

No more terms < A038399(500), which has 26252 digits.

The probability of a number of the order of magnitude of A038399(n) being prime is approximately constant/n^2. Since Sum_n 1/n^2 converges, we should expect this sequence to be finite. (End)

Links

• Eric Weisstein's World of Mathematics, Fibonacci Number
• Eric Weisstein's World of Mathematics, Smarandache Sequences

Crossrefs

Cf. A038399 (concatenation of first n nonzero Fibonacci numbers in reverse order).

Cf. A019523 (concatenation of Fibonacci numbers).

Programs

Maple

count:= 0:
A038399[1]:= 1:
for n from 2 to 100 do
A038399[n]:= combinat:-fibonacci(n)*10^(1+ilog10(A038399[n-1]))+A038399[n-1];
   if isprime(A038399[n]) then count:= count+1; A[count]:= A038399[n] fi
od:
seq(A[i],i=1..count); # Robert Israel, Sep 14 2016

Mathematica

Module[{nn=10,bif},bif=Fibonacci[Range[nn]];Select[Table[FromDigits[ Flatten[ IntegerDigits/@Reverse[Take[bif,n]]]],{n,nn}],PrimeQ]] (* Harvey P. Dale, Sep 27 2019 *)