A218155 Numbers congruent to 2, 3, 6, 11 mod 12.

2, 3, 6, 11, 14, 15, 18, 23, 26, 27, 30, 35, 38, 39, 42, 47, 50, 51, 54, 59, 62, 63, 66, 71, 74, 75, 78, 83, 86, 87, 90, 95, 98, 99, 102, 107, 110, 111, 114, 119, 122, 123, 126, 131, 134, 135, 138, 143, 146, 147, 150, 155, 158, 159, 162, 167, 170, 171, 174

Offset

1,1

Links

Table of n, a(n) for n=1..59.

Index entries for linear recurrences with constant coefficients, signature (2,-2,2,-1).

Formula

a(n) = 2a(n-1) - 2a(n-2) + 2a(n-3) - a(n-4). - Charles R Greathouse IV, Nov 09 2012

G.f.: x^2*(x^3+4*x^2-x+2) / ((x-1)^2*(x^2+1)). - Colin Barker, Jan 07 2013

{m>1|C(m,4)==0 (mod C(m,2))}. - Gary Detlefs, Jan 11 2014

Sum_{n>=1} (-1)^(n+1)/a(n) = (2*sqrt(3)+1)*Pi/24 - log(2+sqrt(3))/(4*sqrt(3)) - log(2)/6. - Amiram Eldar, Mar 18 2022

Mathematica

LinearRecurrence[{2, -2, 2, -1}, {2, 3, 6, 11}, 100] (* T. D. Noe, Nov 11 2012 *)

Prog

(PARI) for(m=2, 175, if(binomial(m, 4)%binomial(m, 2)==0, print1(m, ", "))) \\ Hugo Pfoertner, Aug 11 2020

Crossrefs

Cf. A042944, A042945.

Sequence in context: A337172 A361103 A294510 * A042944 A374913 A361124

Adjacent sequences: A218152 A218153 A218154 * A218156 A218157 A218158

Keyword

nonn,easy

Author

Jean-Claude Babois, Oct 22 2012

Extensions

Edited by Andrey Zabolotskiy, Aug 11 2020

Status

approved