A262996 Ten-digit semiprimes with exactly one 1, two 2's, three 3's and four 4's.

1223444433, 1224343443, 1233444243, 1233444423, 1234424343, 1234442343, 1243344243, 1243442433, 1244332443, 1244343423, 1244344323, 1244442333, 1323442443, 1324244433, 1324344423, 1324443243, 1324443423, 1324444323, 1332244443, 1334244243, 1334244423, 1334424243, 1342443243, 1343242443

Offset: 1

Author

Zak Seidov, Oct 07 2015

Keywords

• nonn
• base
• fini
• full

Comments

From total 10!/(2!*3!*4!)=12600 ten-digit numbers with exactly one 1, two 2's, three 3's and four 4's, exactly 732 numbers are semiprimes of the form 3*prime.

Links

• Zak Seidov, Table of n, a(n) for n = 1..732

Crossrefs

Cf. A022915.

Programs

Mathematica

Select[(FromDigits[#] & /@ Permutations[{1, 2, 2, 3, 3, 3, 4, 4, 4, 4}]), PrimeQ[#/3] &]

PARI

forprime(p=407814811, 1481443741, d=digits(3*p); if(vecsort(d)==[1, 2, 2, 3, 3, 3, 4, 4, 4, 4], print1(3*p", "))) \\ Charles R Greathouse IV, Sep 24 2015