login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A262996 Ten-digit semiprimes with exactly one 1, two 2's, three 3's and four 4's. 1

%I

%S 1223444433,1224343443,1233444243,1233444423,1234424343,1234442343,

%T 1243344243,1243442433,1244332443,1244343423,1244344323,1244442333,

%U 1323442443,1324244433,1324344423,1324443243,1324443423,1324444323,1332244443,1334244243,1334244423,1334424243,1342443243,1343242443

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

%C 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.

%H Zak Seidov, <a href="/A262996/b262996.txt">Table of n, a(n) for n = 1..732</a>

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

%o (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

%Y Cf. A022915.

%K nonn,base,fini,full

%O 1,1

%A _Zak Seidov_, Oct 07 2015

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 23 07:29 EST 2022. Contains 350509 sequences. (Running on oeis4.)