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!)
A075703 a(n) = maximal m such that Sum_{k=n..m} prime(k) <= prime(n)*prime(m). 2
3, 6, 11, 16, 25, 28, 38, 43, 51, 64, 70, 83, 90, 95, 105, 117, 131, 134, 148, 158, 161, 174, 182, 196, 212, 225, 228, 235, 238, 248, 277, 287, 302, 305, 325, 332, 343, 355, 364, 380, 391, 394, 414, 419, 428, 433, 463, 486, 495, 498, 506, 519, 524, 544, 556 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..3000

Felice Russo, On a problem concerning the Smarandache friendly prime pairs.

MAPLE

Primes:= [seq(ithprime(i), i=1..1000)]:

S:= ListTools:-PartialSums(Primes):

f:= proc(n) local m, t;

    for m from n do if S[m] > S[n-1] + Primes[n]*Primes[m] then return m-1 fi od

end proc:

f(1):= 3:

map(f, [$1..100]); # Robert Israel, Aug 08 2019

MATHEMATICA

f[n_] := Block[{k = n, s = 0, a = Prime[n]}, While[b = Prime[k]; s = s + b; a*b >= s, k++ ]; k--; k]; Table[ f[n], {n, 1, 55}]

CROSSREFS

Cf. A074968.

Sequence in context: A116940 A278100 A087099 * A267583 A277023 A034029

Adjacent sequences:  A075700 A075701 A075702 * A075704 A075705 A075706

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Oct 02 2002

EXTENSIONS

Edited by N. J. A. Sloane and Robert G. Wilson v, Oct 04 2002

Corrected by Robert Israel, Aug 08 2019

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 25 17:19 EDT 2020. Contains 334595 sequences. (Running on oeis4.)