A225151 Squares which are a decimal concatenation of triprimes.

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

Author

Kevin L. Schwartz and Christian N. K. Anderson, Apr 30 2013

Keywords

• nonn
• base

Examples

			a(10) is 75076, which splits into 75|076. 75 = 3*5*5; 76 = 2*2*19.
		

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

Crossrefs

Cf. A014612, A030459, A030461, A000290, A019547.

Programs

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