cp's OEIS Frontend

A328587 Numbers n for which A257993(A276086(A276086(n))) is less than A257993(n), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.

%I A328587 #12 Oct 27 2019 17:31:31
%S A328587 12,24,30,42,54,60,72,84,90,102,114,120,132,144,150,162,174,180,192,
%T A328587 204,210,216,228,246,258,276,288,306,318,336,348,366,378,396,408,420,
%U A328587 432,444,450,462,474,480,492,504,510,522,534,540,552,564,570,582,594,600,612,624,636,648,666,678,696,708,726,738,756,768,786,798,816
%N A328587 Numbers n for which A257993(A276086(A276086(n))) is less than A257993(n), where A276086 converts the primorial base expansion of n into its prime product form, and A257993 returns the index of the least prime not present in its argument.
%C A328587 Numbers n for which A328578(n) is less than A257993(n).
%C A328587 All terms are multiples of 6. The final digit {0, 2, 4, 6, 8} of the decimal representation seems to be quite evenly distributed.
%C A328587 Other multiples of six are in A328586 and A328589.
%C A328587 210 is the first term not present in A328632.
%H A328587 Antti Karttunen, <a href="/A328587/b328587.txt">Table of n, a(n) for n = 1..10000</a>
%H A328587 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%o A328587 (PARI)
%o A328587 A257993(n) = { for(i=1,oo,if(n%prime(i),return(i))); }
%o A328587 A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
%o A328587 A328578(n) = A257993(A276086(A276086(n)));
%o A328587 isA328587(n) = (A328578(n) < A257993(n));
%Y A328587 Union of A328632 \ {0} and A328762.
%Y A328587 Positions of negative terms in A328590.
%Y A328587 Cf. A257993, A276086, A328578, A328585, A328586, A328588.
%K A328587 nonn
%O A328587 1,1
%A A328587 _Antti Karttunen_, Oct 21 2019