A096595 -id:A096595 - cp's OEIS frontend

A121342 Composite numbers that are a concatenation of their distinct prime divisors in some order.

735, 3792, 1341275, 13115375, 22940075, 29373375, 71624133, 311997175, 319953792, 1019127375, 1147983375, 1734009275, 5581625072, 7350032375, 17370159615, 33061224492, 103375535837, 171167303912, 319383665913, 533671737975, 2118067737975, 3111368374257

Offset: 1

Tanya Khovanova, Aug 28 2006

Larger terms of this sequence were calculated by Giovanni Resta and Farideh Firoozbakht. This sequence is a subsequence of A083360 (Subsequence of sequence A083359 in which factors do not overlap in the number), which is a subsequence of A083359 (Visible Factor Numbers, or VPNs: numbers n with the property that every prime factor of n can be found in the decimal expansion of n and every digit of n can be found in a prime factor. No additional 0's and 1's are allowed). Also, this sequence is a subsequence of A096595 (Numbers n with the property that n is an anagram of the digits of the distinct prime factors of n).

			For example: 735 = 3*5*7^2 and 3792 = 2^4*3*79.

Giovanni Resta, Table of n, a(n) for n = 1..30

Cf. A083359, A083360, A083361, A096595.

fQ[n_] := !PrimeQ@n && MemberQ[ FromDigits /@ (Flatten@# & /@ IntegerDigits[ Permutations[ First /@ FactorInteger@n]]), n]; Do[ If[fQ@n, Print@n], {n, 10^7/4}] (* Robert G. Wilson v, Sep 02 2006 *)

isok(n) = {if (isprime(n), return (0)); my(vp = factor(n)[,1], nb = #vp); for (i=0, nb!-1, my(vperm = numtoperm(nb, i), s = ""); for (i=1, #vperm, s = concat(s, vp[vperm[i]]);); if (eval(s) == n, return (1));); return (0);} \\ Michel Marcus, Feb 19 2019

a(14) from Emmanuel Vantieghem, Nov 30 2016
Missing term 5581625072=5581||62507||2 inserted by Deron Stewart, Feb 15 2019
a(16)-a(22) from Giovanni Resta, Mar 04 2019

cp's OEIS Frontend

A121342 Composite numbers that are a concatenation of their distinct prime divisors in some order.

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