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 A169791 Least number k having n distinct representations as the sum of a nonzero Fibonacci number and a prime. 2

%I

%S 9,3,4,8,24,74,444,1614,15684,29400,50124,556274,5332128,11110428,

%T 50395440,509562294,1296895890,13314115434,187660997904,326585290794,

%U 4788143252148

%N Least number k having n distinct representations as the sum of a nonzero Fibonacci number and a prime.

%C We count ordered index pairs (i,j) that represent k = Fibonacci(i) + prime(j), i >= 1, j >= 1.

%C A variant of A168382, because Fibonacci(1)=1 and Fibonacci(2)=1 may both contribute individually to the count.

%C Fibonacci(1) + prime(4) = Fibonacci(2) + prime(4) = Fibonacci(4) + prime(3) = Fibonacci(5) + prime(2) = 8 are four "distinct" representations of k=8, because Fibonacci(1) = Fibonacci(2) are treated as distinguishable.

%C a(18) > 10^10. [_Donovan Johnson_, May 17 2010]

%C Except for a(1), all terms appear to be of the form p+1 for some prime p. - _Chai Wah Wu_, Dec 06 2019

%e 1+443 = 1+443 = 5+439 = 13+431 = 55+389 = 233+211 = 377+67 are n=7 distinct representations of k=444.

%Y Cf. A168382, A169790.

%K nonn,more

%O 1,1

%A _R. J. Mathar_ and _Jon E. Schoenfield_, May 14 2010

%E a(12)-a(15) from _Max Alekseyev_, May 15 2010

%E a(16)-a(17) from _Donovan Johnson_, May 17 2010

%E A prime index in the comment corrected by _R. J. Mathar_, Jun 02 2010

%E a(18) from _Chai Wah Wu_, Dec 06 2019

%E a(19)-a(21) from _Giovanni Resta_, Dec 10 2019

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Last modified August 10 03:38 EDT 2022. Contains 356029 sequences. (Running on oeis4.)