login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A372242
a(n) = 10*Fibonacci(n) + (-1)^n.
1
1, 9, 11, 19, 31, 49, 81, 129, 211, 339, 551, 889, 1441, 2329, 3771, 6099, 9871, 15969, 25841, 41809, 67651, 109459, 177111, 286569, 463681, 750249, 1213931, 1964179, 3178111, 5142289, 8320401, 13462689, 21783091, 35245779, 57028871, 92274649, 149303521, 241578169
OFFSET
0,2
FORMULA
Floor(a(n+2)/10) = A052952(n).
a(n) = 1 + A153382(n).
a(n) = 2*A371843(n) - (-1)^n.
a(n) = A022093(n) + (-1)^n.
G.f.: -(9*x^2+9*x+1)/((x+1)*(x^2+x-1)).
a(0) = 1. a(n) = -a(n-1) + 10*A000045(n+1) for n >= 1.
a(n) = a(n-4) + (2*A280154(n-2) = 5*A022112(n-3) = 10*A000032(n-2)) for n >= 4.
EXAMPLE
a(0) = 10*0 + 1 = 1,
a(1) = 10*1 - 1 = 9,
a(2) = 10*1 + 1 = 11,
a(3) = 10*2 - 1 = 19.
MATHEMATICA
LinearRecurrence[{0, 2, 1}, {1, 9, 11}, 50] (* Paolo Xausa, May 20 2024 *)
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Apr 23 2024
STATUS
approved