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A225151
Squares which are a decimal concatenation of triprimes.
1
12544, 15376, 19044, 20164, 27556, 28561, 42436, 45369, 45796, 75076, 81796, 86436, 87025, 89401, 98596, 114244, 116964, 123201, 124609, 125316, 126025, 127449, 128164, 131044, 139876, 141376, 150544, 174724, 175561, 184041, 188356, 190969, 191844, 207025
OFFSET
1,1
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
STATUS
approved