OFFSET
1,1
COMMENTS
A number n is in this sequence if the sums of distinct divisors of n form all the primes up to sigma(n), but do not form all the integers up to sigma(n).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..2000
MATHEMATICA
Test[n_] := Module[{d=Divisors[n], t, lim, x}, t=CoefficientList[Product[1+x^i, {i, d}], x]; lim=PrimePi[Length[t]-1]; Count[t[[1+Prime[Range[lim]]]], _?(#>0&)] == lim && Count[t, 0] > 0]; Select[Range[1000], Test]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Mar 19 2010
STATUS
approved