The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A268044 The odd numbers congruent to {3, 4} mod 5. 1
 3, 9, 13, 19, 23, 29, 33, 39, 43, 49, 53, 59, 63, 69, 73, 79, 83, 89, 93, 99, 103, 109, 113, 119, 123, 129, 133, 139, 143, 149, 153, 159, 163, 169, 173, 179, 183, 189, 193, 199, 203, 209, 213, 219, 223, 229, 233, 239, 243, 249, 253, 259, 263, 269, 273, 279, 283, 289, 293, 299 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The odd numbers with terminal digit 3 or 9. LINKS Table of n, a(n) for n=1..60. Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA G.f.: x*(3 + 6*x + x^2)/((1 + x)*(1 - x)^2). a(n) = a(n-1) + a(n-2) - a(n-3). a(n) = 5*n - (3 - (-1)^n)/2. a(n) = -A131229(-n+1) with A131229(0) = -3. Sum_{n>=1} (-1)^(n+1)/a(n) = sqrt((5+sqrt(5))/2)*Pi/10 - 3*log(phi)/(2*sqrt(5)), where phi is the golden ratio (A001622). - Amiram Eldar, Apr 15 2023 MATHEMATICA Table[5 n - (3 - (-1)^n)/2, {n, 1000}] (* or *) Select[ Range [1000], OddQ[#] && MemberQ[{3, 4}, Mod[#, 5]] &] LinearRecurrence[{1, 1, -1}, {3, 9, 13}, 60] (* Harvey P. Dale, Feb 12 2023 *) PROG (Magma) [5*n-(3-(-1)^n)/2: n in [1..60]]; // Vincenzo Librandi, Jan 25 2016 CROSSREFS Cf. A001622, A005408, A045435, A047204, A131229. Second bisection of A045572. Sequence in context: A095234 A240240 A032415 * A190745 A075318 A171101 Adjacent sequences: A268041 A268042 A268043 * A268045 A268046 A268047 KEYWORD nonn,easy AUTHOR Mikk Heidemaa, Jan 25 2016 EXTENSIONS Edited by Bruno Berselli, Jan 25 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 21 14:36 EST 2024. Contains 370235 sequences. (Running on oeis4.)