cp's OEIS Frontend

A367187 Numbers which are the sum of a prime number and a Fibonacci number of index >1 in at least two ways.

%I A367187 #30 Dec 04 2023 21:08:04
%S A367187 4,5,6,7,8,10,12,13,14,15,16,18,19,20,21,22,24,25,26,28,30,31,32,34,
%T A367187 36,37,38,39,40,42,44,45,46,48,49,50,51,52,54,55,56,57,58,60,61,62,63,
%U A367187 64,66,68,69,72,74,75,76,78,80,81,82,84,86,87,88,91,92,94,96,98,100
%N A367187 Numbers which are the sum of a prime number and a Fibonacci number of index >1 in at least two ways.
%e A367187 4 is a term since 4 = 1+3 = 2+2.
%e A367187 5 is a term since 5 = 2+3 = 3+2.
%e A367187 57 is a term since 57 = 2+55 = 23+34.
%o A367187 (PARI) isfib(n) = if (n>0, my(k=n^2); k+=(k+1)<<2; issquare(k) || issquare(k-8));
%o A367187 isok(k) = sum(i=1, primepi(k), isfib(k-prime(i))) > 1; \\ _Michel Marcus_, Nov 09 2023
%Y A367187 Cf. A000040, A000045, A367186.
%Y A367187 Subsequence of A132147.
%K A367187 nonn
%O A367187 1,1
%A A367187 _Yuda Chen_, Nov 08 2023