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

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064351 Numbers n such that n and n+1 have the same sum and number of prime divisors (with repetition). 1
6867, 57075, 113283, 155708, 230124, 244035, 250995, 351075, 437715, 508563, 667628, 742508, 1065843, 1095315, 1166067, 1302092, 1379907, 1431212, 1496780, 2373452, 2519343, 2978787, 2992220, 3164524, 3583772, 4799011, 4826835, 5103875, 5140316, 5535404 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Harry J. Smith and Donovan Johnson, Table of n, a(n) for n = 1..1000 (first 80 terms from Harry J. Smith)
MATHEMATICA
snpd[n_]:=Module[{fi=FactorInteger[n]}, {Total[Flatten[Table[#[[1]], {#[[2]]}]&/@fi]], Total[Transpose[fi][[2]]]}]; Flatten[Position[Partition[ Array[ snpd, 5600000], 2, 1], _?(#[[1]]==#[[2]]&), {1}, Heads->False]] (* Harvey P. Dale, Nov 29 2013 *)
PROG
(PARI) sopfr(n)= { local(c, f, s=0); G=0; f=factor(n); for(i=1, matsize(f)[1], c=f[i, 2]; G+=c; s+=f[i, 1]*c); return(s) } { n=c=s=0; for (m=1, 10^9, us=sopfr(m + 1); if(c==G && s==us, write("b064351.txt", n++, " ", m); if (n==100, break)); c=G; s=us ) } \\ Harry J. Smith, Sep 12 2009
CROSSREFS
Sequence in context: A013811 A013892 A154086 * A366205 A345148 A345149
KEYWORD
nonn
AUTHOR
Jason Earls, Oct 15 2001
EXTENSIONS
a(25) - a(27) from Harry J. Smith, Sep 12 2009
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)