OFFSET
0,1
COMMENTS
Successive differences begin:
2, 0, 1, -1, 3, -3, 6, -10, 15, -25, ... = a(n)
-2, 1, -2, 4, -6, 9, -16, 25, -40, 66, ... = b(n)
3, -3, 6, -10, 15, -25, 41, -65, 106, -172, ... = a(n+4)
-6, 9, -16, 25, -40, 66, -106, 171, -278, 449, ... = b(n+4)
15, -25, 41, -65, 106, -172, 277, -449, 727, -1175, ... = a(n+8)
...
Main diagonal [2] 1, 6, 25, 106, 449, ... (omitting first term) is A048875 (Pellian numbers with second term 6).
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,1,-2,1).
FORMULA
MATHEMATICA
LinearRecurrence[{0, 1, -2, 1}, {2, 0, 1, -1}, 40]
PROG
(PARI) x='x+O('x^99); Vec((2-x^2+3*x^3)/(1-x^2+2*x^3-x^4)) \\ Altug Alkan, Sep 18 2017
CROSSREFS
KEYWORD
sign
AUTHOR
Jean-François Alcover and Paul Curtz, Sep 18 2017
STATUS
approved