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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A108274 Sum of the first 10^n terms in A097974. a(n) = sum_{m=1..10^n} t(m), where t(m) is the sum of the prime divisors of m that are less than or equal to sqrt(m). 1
0, 11, 327, 7714, 184680, 4617253, 118697919, 3149768778, 85356405077, 2357169671137, 66097467843823, 1875931900135854, 53804720498131760, 1556256544987695973, 45343922927650954928, 1329347125287604758708, 39180941384720954859005 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Does a(n+1)/a(n) converge?

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 0..19

EXAMPLE

The first 10^2 terms in A097974 sum to 327, so a(2) = 327.

MATHEMATICA

s = 0; k = 1; Do[s += Plus @@ Select[Select[Divisors[n], PrimeQ], #<=Sqrt[n] &]; If[n == k, Print[s]; s = 0; k *= 10], {n, 1, 10^7}]

PROG

(PARI) a(n) = sum(m=1, 10^n, sumdiv(m, d, d*isprime(d)*(d<=sqrt(m)))); \\ Michel Marcus, Jul 07 2014

CROSSREFS

Cf. A097974.

Sequence in context: A197448 A241127 A268551 * A295171 A254545 A160293

Adjacent sequences:  A108271 A108272 A108273 * A108275 A108276 A108277

KEYWORD

nonn

AUTHOR

Ryan Propper, Jul 24 2005

EXTENSIONS

a(2)-a(7) and the example corrected and a(8)-a(16) from Hiroaki Yamanouchi, Jul 07 2014

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 January 17 06:41 EST 2019. Contains 319207 sequences. (Running on oeis4.)