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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A365424 a(1) = 1, a(3^k) = 3 for k >= 1, and for any other n, a(n) is the last prime that is selected when the value of A356867(n) is computed with a greedy algorithm. 2
 1, 2, 3, 5, 2, 2, 2, 2, 3, 7, 7, 5, 5, 5, 2, 5, 2, 2, 5, 2, 2, 5, 2, 2, 2, 2, 3, 11, 11, 7, 11, 11, 7, 7, 7, 5, 7, 7, 5, 7, 7, 5, 5, 5, 2, 7, 7, 5, 5, 5, 2, 5, 2, 2, 7, 5, 5, 5, 2, 2, 5, 2, 2, 7, 5, 5, 5, 2, 2, 5, 2, 2, 5, 2, 2, 5, 2, 2, 2, 2, 3, 13, 13, 11, 13, 13, 11, 13, 13, 7, 13, 11, 11, 13, 11, 11, 11, 11, 7 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Apparently the analogous sequence for Doudna variant D(2) (A005940) is 1 followed by A000040(A290251(n-1)) for n >= 2: 1, 2, 3, 2, 5, 3, 3, 2, 7, 5, 5, 3, 5, 3, 3, 2, 11, 7, 7, 5, 7, etc. LINKS Antti Karttunen, Table of n, a(n) for n = 1..59049 FORMULA a(1) = 1, and for n > 1, if n is of the form 3^k, then a(n) = 3, otherwise a(n) = A356867(n) / A356867(A365459(n)). PROG (PARI) up_to = (3^10); A365424list(up_to) = { my(v=vector(up_to), pv=vector(up_to), met=Map(), h=0, ak); for(i=1, #v, if(1==sumdigits(i, 3), v[i] = i; pv[i] = if(1==i, i, 3); h = i, ak = v[i-h]; forprime(p=2, , if(3!=p && !mapisdefined(met, p*ak), v[i] = p*ak; pv[i] = p; break))); mapput(met, v[i], i)); (pv); }; v365424 = A365424list(up_to); A365424(n) = v365424[n]; CROSSREFS Cf. A000040, A000244 (positions of the initial 1 and all 3's), A053735, A356867, A365459. Cf. also A005940, A290251. Sequence in context: A269701 A011157 A205387 * A060441 A255913 A065996 Adjacent sequences: A365421 A365422 A365423 * A365425 A365426 A365427 KEYWORD nonn AUTHOR Antti Karttunen, Sep 17 2023 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 September 9 22:43 EDT 2024. Contains 375765 sequences. (Running on oeis4.)