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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A045940 Numbers n such that the factorizations of n through n+3 have the same number of primes (including multiplicities). 10
602, 603, 1083, 2012, 2091, 2522, 2523, 2524, 2634, 2763, 3243, 3355, 4023, 4202, 4203, 4921, 4922, 4923, 5034, 5035, 5132, 5203, 5282, 5283, 5785, 5882, 5954, 5972, 6092, 6212, 6476, 6962, 6985, 7314, 7730, 7731, 7945, 8393, 8825, 8956, 8972, 9162 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Zak Seidov and Michael De Vlieger, Table of n, a(n) for n = 1..11998 (First 3356 terms from Zak Seidov)

MATHEMATICA

f[n_]:=Plus@@Last/@FactorInteger[n]; lst={}; lst={}; Do[If[f[n]==f[n+1]==f[n+2]==f[n+3], AppendTo[lst, n]], {n, 0, 8!}]; lst (* Vladimir Joseph Stephan Orlovsky, May 12 2010 *)

SequencePosition[PrimeOmega[Range[10000]], {x_, x_, x_, x_}][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 02 2020 *)

PROG

(PARI) isok(n) = (bigomega(n) == bigomega(n+1)) && (bigomega(n+1) == bigomega(n+2)) && (bigomega(n+2) == bigomega(n+3)); \\ Michel Marcus, Jan 06 2015

CROSSREFS

Cf. A045932 (similar with omega), A045939 (similar up to n+2),

Sequence in context: A292069 A107440 A218055 * A124057 A252435 A045941

Adjacent sequences:  A045937 A045938 A045939 * A045941 A045942 A045943

KEYWORD

nonn

AUTHOR

David W. Wilson

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 12 22:58 EDT 2021. Contains 343829 sequences. (Running on oeis4.)