A074254 Composite numbers equal to the sum of the squarefree numbers from their smallest prime factor to their largest prime factor.

10, 21, 44, 3317, 200632, 1110101, 975558109

Offset

1,1

Comments

The next term is greater than 4*10^9. - Robert Gerbicz, Jun 09 2007

Links

Table of n, a(n) for n=1..7.

Example

44 = 2^2*11 = 2+3+5+6+7+10+11.

Prog

(PARI) a=vector(10^5); a[1]=1; for(n=2, 10^5, a[n]=a[n-1]+n*abs(moebius(n))); forprime(p=2, 10^5, forprime(q=p+1, 10^5, n=a[q]-a[p-1]; if((n%q==0)&&(n%p==0), k=n/(p*q); u=factor(k); w=matsize(u); if((w[1]==0)||(u[1, 1]>=p)&&(u[w[1], 1]<=q), print(n))))) - Robert Gerbicz, Jun 09 2007

Crossrefs

Sequence in context: A086225 A240994 A014007 * A122963 A067520 A219884

Adjacent sequences: A074251 A074252 A074253 * A074255 A074256 A074257

Keyword

nonn

Author

Jason Earls, Sep 20 2002

Extensions

3 more terms from Robert Gerbicz, Jun 09 2007

Status

approved