login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064798 Sum of primes dividing the repunit numbers (with repetition). 1
0, 0, 11, 40, 112, 312, 71, 4888, 322, 333710, 9414, 534888, 10073, 265371785, 913990, 2906544, 5882692, 5365294080, 386339, 1111111111111111111, 41017, 10845593, 547805, 11111111111111111111111, 100000284, 182521260315 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Giovanni Resta, Table of n, a(n) for n = 0..322 (first 101 terms from Harry J. Smith)

MATHEMATICA

a[n_] := If[n < 2, 0, Total[Times @@@ FactorInteger[Floor[10^n/9]]]]; Array[a, 30, 0] (* Giovanni Resta, Jul 19 2018 *)

PROG

(PARI) a(n) = (10^n-1)/9; {sopfr(n, s, fac, i) = fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]*fac[i, 2]); return(s); } for(n=0, 35, print1(sopfr(a(n)), ", "))

(PARI) sopfr(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]*f[i, 2]); return(s) } { for (n=0, 100, write("b064798.txt", n, " ", sopfr((10^n - 1)/9)) ) } \\ Harry J. Smith, Sep 26 2009

CROSSREFS

Cf. A002275, A001414.

Sequence in context: A031427 A147296 A059142 * A056124 A225919 A064768

Adjacent sequences:  A064795 A064796 A064797 * A064799 A064800 A064801

KEYWORD

nonn,base

AUTHOR

Jason Earls, Oct 18 2001

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 December 17 05:30 EST 2018. Contains 318192 sequences. (Running on oeis4.)