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A074195 Sum of the primes from smallest prime factor of n to the largest prime factor of n = largest difference between consecutive divisors of n (ordered by size). 0
4, 20, 1278, 1339, 11074308238, 19096347067 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
10^11 < a(7) <= 8912510129422438. - Giovanni Resta, May 13 2016
LINKS
MATHEMATICA
Select[Range[2, 2000], (p = First /@ FactorInteger[#]; #-#/p[[1]] == Sum[ Prime[i], {i, PrimePi@ p[[1]], PrimePi@ p[[-1]]}]) &] (* Giovanni Resta, May 13 2016 *)
PROG
(PARI) isok(n) = {pf = factor(n)[, 1]; my(pmin = vecmin(pf)); s = 0; forprime(p = pmin, vecmax(pf), s += p); s == n - n/pmin; } \\ Michel Marcus, Feb 03 2014
CROSSREFS
Sequence in context: A132511 A144989 A012841 * A332867 A217369 A146342
KEYWORD
more,nonn
AUTHOR
Jason Earls, Sep 19 2002
EXTENSIONS
a(5)-a(6) from Giovanni Resta, May 13 2016
STATUS
approved

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Last modified July 21 16:38 EDT 2024. Contains 374475 sequences. (Running on oeis4.)