A046396 - OEIS

%I #19 Jun 07 2024 14:25:17

%S 222222,282282,474474,555555,606606,646646,969969,2040402,2065602,

%T 2206022,2417142,2646462,2673762,2875782,3262623,3309033,4179714,

%U 4192914,4356534,4585854,4912194,5021205,5169615,5174715,5578755

%N Palindromes which are the product of 6 distinct primes.

%C The original definition "Palindromes with exactly 6 distinct prime factors" was misleading. For example, the number 414414 = 2 * 3^2 * 7 * 11 * 13 * 23 has exactly 6 distinct prime factors, although the factor 3 occurs twice. But the listed terms show that it is not in this sequence. See sequence A373466 for the variant corresponding to that definition. - _M. F. Hasler_, Jun 06 2024

%F Intersection of A002113 and A067885. - _M. F. Hasler_, Jun 06 2024

%t Select[Range[6*10^6],#==IntegerReverse[#]&&PrimeNu[#]==PrimeOmega[#]==6&] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* _Harvey P. Dale_, Mar 17 2016 *)

%o (PARI) A046332_upto(N, start=1, num_fact=6)={ my(L=List()); while(N >= start = nxt_A002113(start), omega(start)==num_fact && issquarefree(start) && listput(L, start)); L} \\ _M. F. Hasler_, Jun 06 2024

%Y Cf. A046332 (similar, but for 6 prime factors counted with multiplicity).

%Y Cf. A002113 (palindromes), A067885 (products of 6 distinct primes).

%Y Cf. A074969 (numbers having 6 distinct prime divisors).

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Jun 15 1998

%E Name edited