OFFSET
1,1
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
EXAMPLE
MATHEMATICA
a=30; b=42; c=66; L={}; While[ Length[L]<100, If[b-a == c-b, AppendTo[L, b]]; a=b; b=c++; While[ Last/@ FactorInteger[c] != {1, 1, 1}, c++]]; L (* Giovanni Resta, Jun 09 2015 *)
PROG
(PARI)
issphenic(n)=if(n>0, omega(n)==3&&bigomega(n)==3, 0)
nextsph(n)={local(k=n+1); while(!issphenic(k), k+=1); k}
precsph(n)={local(k=n-1); while(!issphenic(k)&&k>0, k-=1); k}
{for(i=1, 4*10^3, if(issphenic(i)&&2*i== nextsph(i)+ precsph(i), print1(i, ", ")))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Antonio Roldán, May 25 2015
STATUS
approved