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%I #14 May 25 2024 10:42:00
%S 72,260,380,620,740,860,1220,1340,1460,1580,1940,2060,2180,2540,2780,
%T 3020,3140,3260,3620,3860,3980,4220,4460,4580,4820,5420,5540,5660,
%U 6140,6260,6620,6740,6980,7340,7460,7580,7940,8180,8420,8660,8780,9140,9260,9740,9980,10460,10820,10940,11420,11540,12020,12140,12260
%N Positions of -4's in A346242.
%C Term a(94)=23256 is the first term after 72 that is not a multiple of 20. The first four odd terms 71825, 942667, 1322035, 3613027 occur at indices n=273, 3355, 4619, 11995.
%C Of the first 20000 terms, 13422 are multiples of 20, and apparently, for any n > 1, 20*A002476(n) is included in this sequence.
%H Antti Karttunen, <a href="/A372564/b372564.txt">Table of n, a(n) for n = 1..20000</a>
%H <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%o (PARI)
%o A324198(n) = { my(m=1, p=2, orgn=n); while(n, m *= (p^min(n%p, valuation(orgn, p))); n = n\p; p = nextprime(1+p)); (m); };
%o memoA346242 = Map();
%o A346242(n) = if(1==n,1,my(v); if(mapisdefined(memoA346242,n,&v), v, v = -sumdiv(n,d,if(d<n,A324198(n/d)*A346242(d),0)); mapput(memoA346242,n,v); (v)));
%o isA372564(n) = (-4==A346242(n));
%Y Cf. A002476, A346242.
%Y Cf. also A354814.
%K nonn
%O 1,1
%A _Antti Karttunen_, May 24 2024