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A368698 a(n) is the smallest positive k such that A005940(1+n) divides the oblong number k*(k+1).

%I A368698 #12 Jan 12 2024 12:04:54
%S A368698 1,1,2,3,4,2,8,7,6,4,5,3,24,8,26,15,10,6,6,4,14,5,9,8,48,24,24,8,124,
%T A368698 26,80,31,12,10,11,7,10,6,27,15,21,14,14,15,49,9,54,15,120,48,48,24,
%U A368698 49,24,99,8,342,124,125,27,624,80,242,63,16,12,12,11,25,11,44,7,13,10,44,20,99,27,27,15,65,21,21,20
%N A368698 a(n) is the smallest positive k such that A005940(1+n) divides the oblong number k*(k+1).
%H A368698 Antti Karttunen, <a href="/A368698/b368698.txt">Table of n, a(n) for n = 0..16384</a>
%F A368698 a(n) = A344005(A005940(1+n)).
%F A368698 For n >= 1, a(2^n) = A006093(n), a(A000225(n)) = A000225(n).
%o A368698 (PARI)
%o A368698 A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
%o A368698 A344005(n) = { my(m=1); while((m*(m+1)) % n, m++); m; };
%o A368698 A368698(n) = A344005(A005940(1+n));
%Y A368698 Cf. A002378, A005940, A344005, A368699, A368700, A368693 (rgs-transform), A368988 (positions of records), A368989 (values of records).
%K A368698 nonn
%O A368698 0,3
%A A368698 _Antti Karttunen_, Jan 11 2024