OFFSET
1,3
COMMENTS
See the second comment in A265187.
Also, nonnegative m congruent to 0, 1, 5, 6 or 10 (mod 11).
Primes in sequence: 5, 11, 17, 23, 43, 61, 67, 71, 83, 89, 109, 127, ...
LINKS
Bruno Berselli, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).
FORMULA
G.f.: x^2*(1 + 4*x + x^2 + 4*x^3 + x^4)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)).
a(n) = a(n-1) + a(n-5) - a(n-6), n>6.
MATHEMATICA
Select[Range[0, 150], 3 Floor[#^2/11] == Floor[3 #^2/11] &]
Select[Range[0, 150], MemberQ[{0, 1, 5, 6, 10}, Mod[#, 11]] &]
LinearRecurrence[{1, 0, 0, 0, 1, -1}, {0, 1, 5, 6, 10, 11}, 70]
PROG
(Sage) [n for n in (0..150) if 3*floor(n^2/11) == floor(3*n^2/11)]
(Magma) [n: n in [0..150] | 3*Floor(n^2/11) eq Floor(3*n^2/11)];
(PARI) is(n) = 3*(n^2\11) == (3*n^2)\11 \\ Anders Hellström, Dec 05 2015
(PARI) concat(0, Vec(x^2*(1 + 4*x + x^2 + 4*x^3 + x^4)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)) + O(x^100))) \\ Michel Marcus, Dec 05 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Bruno Berselli, Dec 04 2015
STATUS
approved