The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A228299 Composite squarefree numbers n such that p+d(n) divides n+d(n), where p are the prime factors of n and d(n) the number of divisors of n. 16
 21098, 134930, 343027, 361730, 387127, 751394, 793595, 1344517, 1430449, 1579394, 1794854, 3542797, 5022254, 7930117, 9241627, 12122947, 21089129, 21928717, 49825117, 70233329, 78795074, 90079589, 95208734, 110995807, 124648303, 124964219, 144871634 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A120944. LINKS Donovan Johnson, Table of n, a(n) for n = 1..100 EXAMPLE Prime factors of 21098 are 2, 7, 11 and 137 while d(21098) = 16. We have that 21098 + 16 = 21114 and 21114 / (2 + 16) =  1173, 21114 / (7 + 16) = 918, 21114 / (11 + 16) = 782 and 21114 / (137 + 16) = 138. MAPLE with (numtheory); P:=proc(q) local a, i, ok, n; for n from 1 to q do  if not isprime(n) then a:=ifactors(n)[2]; ok:=1; for i from 1 to nops(a) do if a[i][2]>1 then ok:=0; break; else if not type((n+tau(n))/(a[i][1]+tau(n)), integer) then ok:=0; break; fi; fi; od; if ok=1 then print(n); fi; fi; od; end: P(10^6); CROSSREFS Cf. A000005, A228300-A228302. Sequence in context: A181260 A316482 A340897 * A178279 A097239 A270773 Adjacent sequences:  A228296 A228297 A228298 * A228300 A228301 A228302 KEYWORD nonn AUTHOR Paolo P. Lava, Aug 20 2013 EXTENSIONS More terms from Michel Marcus, Sep 21 2013 Deleted first term from Paolo P. Lava, Sep 23 2013 STATUS approved

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

Last modified May 6 21:35 EDT 2021. Contains 343597 sequences. (Running on oeis4.)