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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A326810 The smallest prime that does not divide the prime product form (A276086) of the primorial base expansion of n.

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%I A326810 #25 Oct 22 2019 21:26:51
%S A326810 2,3,2,5,2,5,2,3,2,7,2,7,2,3,2,7,2,7,2,3,2,7,2,7,2,3,2,7,2,7,2,3,2,5,
%T A326810 2,5,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,5,
%U A326810 2,5,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,11,2,11,2,3,2,5,2,5,2,3,2,11,2,11,2,3,2,11
%N A326810 The smallest prime that does not divide the prime product form (A276086) of the primorial base expansion of n.
%H A326810 Antti Karttunen, <a href="/A326810/b326810.txt">Table of n, a(n) for n = 0..32768</a>
%H A326810 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%F A326810 a(n) = A053669(A276086(n)).
%F A326810 a(n) = A000040(A328570(n)).
%F A326810 a(n) = A020639(A276087(n)) = A020639(A328613(n)).
%F A326810 a(n) = A276087(n) / A276086(A328476(n)).
%F A326810 For all odd n, a(n) > A276088(n).
%F A326810 For all n >= 0, a(A276086(n)) = A328579(n).
%F A326810 For all n >= 1, A328317(n) = a(A328316(n-1)).
%t A326810 With[{b = MixedRadix[Reverse@ Prime@ Range@ 12]}, Table[Block[{p = 2}, While[Mod[#, p] == 0, p = NextPrime@ p]; p] &@ Apply[Times, Power @@@ # &@ Transpose@ {Prime@ Range@ Length@ #, Reverse@ #}] &@ IntegerDigits[n, b], {n, 0, 105}]] (* _Michael De Vlieger_, Oct 22 2019 *)
%o A326810 (PARI) A326810(n) = { my(i=1, p=2); while(n && (n%p), n = n\p; p = nextprime(1+p)); (p); };
%Y A326810 Cf. A053669, A143293, A276086, A276087, A276088, A328476, A328570, A328579, A328580.
%Y A326810 Cf. also A328316, A328317, A328613.
%K A326810 nonn
%O A326810 0,1
%A A326810 _Antti Karttunen_, Oct 19 2019