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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A258125 a(1) = a(2) = 2; a(n) = a(n-1) + gpf(a(n-2)), where gpf is greatest prime factor. 1
 2, 2, 4, 6, 8, 11, 13, 24, 37, 40, 77, 82, 93, 134, 165, 232, 243, 272, 275, 292, 303, 376, 477, 524, 577, 708, 1285, 1344, 1601, 1608, 3209, 3276, 6485, 6498, 7795, 7814, 9373, 13280, 13383, 13466, 14953, 21686, 22473, 24022, 24249, 36260 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Anders Hellström, Table of n, a(n) for n = 1..1000 MATHEMATICA a[1] = a[2] = 2; a[n_] := a[n] = a[n - 1] + FactorInteger[a[n - 2]][[-1, 1]]; Table[a@ n, {n, 46}] (* Michael De Vlieger, Nov 16 2015 *) nxt[{a_, b_}]:={b, b+FactorInteger[a][[-1, 1]]}; Transpose[NestList[nxt, {2, 2}, 50]][[1]] (* Harvey P. Dale, Nov 22 2015 *) PROG (PARI) gpf(n)=my(f=factor(n)[, 1]); f[#f]; first(m)=my(v=vector(m)); v[1]=2; v[2]=2; for(i=3, m, v[i]=v[i-1]+gpf(v[i-2])); v (Haskell) a258125 n = a258125_list !! (n-1) a258125_list = 2 : 2 : zipWith (+) (map a006530 a258125_list) (tail a258125_list) -- Reinhard Zumkeller, Nov 17 2015 CROSSREFS Cf. A006530 (gpf), A078695 (same recurrence). Sequence in context: A179999 A286736 A241383 * A361394 A147982 A329899 Adjacent sequences: A258122 A258123 A258124 * A258126 A258127 A258128 KEYWORD nonn AUTHOR Anders Hellström, Nov 16 2015 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 March 29 08:53 EDT 2023. Contains 361596 sequences. (Running on oeis4.)