OFFSET
1,1
COMMENTS
The sequence snud(a(n)) = snud(1 + a(n)) is A103846(n). - Emeric Deutsch, Feb 17 2005
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..344 (terms < 10^11, first 30 terms from Harry J. Smith)
EXAMPLE
snud(1484) = 864, snud(1485) = 864.
MATHEMATICA
nusigma[1]=0; nusigma[n_] := DivisorSigma[1, n] - Times @@ (1 + Power @@@ FactorInteger[n]); seq={}; s1=0; Do[s2=nusigma[n]; If[s1>0 && s2==s1, AppendTo[seq, n-1]]; s1=s2, {n, 1, 10^6}]; seq (* Amiram Eldar, Jun 10 2019 *)
PROG
(PARI) snud(n)= { sumdiv(n, d, if(gcd(d, n/d)!=1, d)) }
{ n=0; for (m=1, 10^9, s=snud(m); if (s>0 && s==snud(m + 1), write("b064115.txt", n++, " ", m); if (n==30, break)) ) } \\ Harry J. Smith, Sep 07 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Sep 09 2001
EXTENSIONS
More terms from Emeric Deutsch, Feb 17 2005
STATUS
approved