OFFSET
1,1
LINKS
Christian N. K. Anderson, Table of n, a(n) for n = 1..10000
Christian N. K. Anderson, Table of n, a(n), sqrt(a(n)), all possible separations of a(n) into triprimes
EXAMPLE
a(10) is 75076, which splits into 75|076. 75 = 3*5*5; 76 = 2*2*19.
PROG
(R) library(gmp); istriprime=function(x) ifelse(x<8, F, length(factorize(x))==3)
splithasproperty<-function(n, FUN, curdig=1, res=list(), curspl=c()) {
no0<-function(s){ while(substr(s, 1, 1)=="0" & nchar(s)>1) s=substr(s, 2, nchar(s)); s}
s=as.character(n)
if(curdig>nchar(s)) return(res)
if(length(curspl)>0) if(FUN(as.bigz(no0(substr(s, curdig, nchar(s)))))) res[[length(res)+1]]=curspl
for(i in curdig:nchar(s))
if(FUN(as.bigz(no0(substr(s, curdig, i)))))
res=splithasproperty(n, FUN, i+1, res, c(curspl, i))
res
}
which(sapply(1:500, function(x) length(splithasproperty(x^2, istriprime)))>0)^2
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Kevin L. Schwartz and Christian N. K. Anderson, Apr 30 2013
STATUS
approved