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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A359239 Number of divisors of 3*n-2 of form 3*k+2. 7
 0, 1, 0, 2, 0, 2, 0, 2, 1, 2, 0, 2, 0, 4, 0, 2, 0, 2, 2, 2, 0, 3, 0, 4, 0, 2, 0, 2, 2, 4, 0, 2, 0, 4, 0, 2, 0, 4, 2, 2, 1, 2, 0, 4, 0, 4, 0, 2, 2, 2, 0, 4, 0, 6, 0, 2, 0, 2, 2, 2, 0, 4, 2, 4, 0, 3, 0, 2, 2, 4, 0, 2, 0, 6, 0, 2, 0, 4, 2, 4, 0, 2, 0, 4, 2, 4, 0, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Table of n, a(n) for n=1..90. FORMULA a(n) = A001822(3*n-2). G.f.: Sum_{k>0} x^(2*k)/(1 - x^(3*k-1)). MATHEMATICA Table[Count[Divisors[3 n-2], _?(IntegerQ[(#-2)/3]&)], {n, 100}] (* Harvey P. Dale, Apr 23 2023 *) a[n_] := DivisorSum[3*n-2, 1 &, Mod[#, 3] == 2 &]; Array[a, 100] (* Amiram Eldar, Aug 23 2023 *) PROG (PARI) a(n) = sumdiv(3*n-2, d, d%3==2); (PARI) my(N=100, x='x+O('x^N)); concat(0, Vec(sum(k=1, N, x^(2*k)/(1-x^(3*k-1))))) CROSSREFS Cf. A001822, A359211, A359212. Cf. A359240, A359241. Sequence in context: A227957 A305575 A247977 * A143232 A329981 A096030 Adjacent sequences: A359236 A359237 A359238 * A359240 A359241 A359242 KEYWORD nonn,easy AUTHOR Seiichi Manyama, Dec 22 2022 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 August 14 00:08 EDT 2024. Contains 375146 sequences. (Running on oeis4.)