2. Fibonacci-like approach for the row 4, 4, 7, X, 103

F(n) = a*F(n-2) + b*F(n-1) + c with F(0) = 4 and F(1) = 4

Applied accordingly it results:
F(2) = a*F(0) + b*F(1) + c = 4a + 4b + c = 7
F(3) = a*F(1) + b*F(2) + c = 4a + 7b + c = X
F(4) = a*F(2) + b*F(3) + c = 7a + Xb + c = 103

Solving this system of equations delivers the parameters depending on X:
a = (-X² + 11X + 260) / 9
b = (X - 7) / 3
c = (4X² - 56X - 893) / 9

So you get solutions for whole-numbered X in the form of 3*k+7 (k≠0, since otherwise due to b=0 there is no link to F(1).) with whole-numbered continuations after the 103.

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