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A337643 a(1) = 1; thereafter a(n) = a(n-1) / lpf(n) if lpf(n) divides a(n-1), otherwise a(n) = a(n-1) * lpf(n), where lpf is the least prime factor function A020639.

%I A337643 #6 Sep 22 2020 00:28:07
%S A337643 1,1,2,6,3,15,30,210,105,35,70,770,385,5005,10010,30030,15015,255255,
%T A337643 510510,9699690,4849845,1616615,3233230,74364290,37182145,7436429,
%U A337643 14872858,44618574,22309287,646969323,1293938646,40112098026,20056049013,6685349671,13370699342
%N A337643 a(1) = 1; thereafter a(n) = a(n-1) / lpf(n) if lpf(n) divides a(n-1), otherwise a(n) = a(n-1) * lpf(n), where lpf is the least prime factor function A020639.
%p A337643 A020639 := proc(n) if n = 1 then 1; else min(op(numtheory[factorset](n))) ; end if; end proc:
%p A337643 a:=[1]; t:=1;
%p A337643 for n from 2 to 50 do
%p A337643 u:=A020639(n-1);
%p A337643 if (t mod u) = 0 then t:=t/u else t:=t*u; fi; a:=[op(a),t];
%p A337643 od;
%p A337643 a;
%Y A337643 Cf. A020639, A326889, A327442, A336823.
%K A337643 nonn
%O A337643 1,3
%A A337643 _N. J. A. Sloane_, Sep 21 2020