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

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, 26, 80, 31, 12, 10, 11, 7, 10, 6, 27, 15, 21, 14, 14, 15, 49, 9, 54, 15, 120, 48, 48, 24, 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

Offset: 0

Author

Antti Karttunen, Jan 11 2024

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 0..16384

Crossrefs

Cf. A002378, A005940, A344005, A368699, A368700, A368693 (rgs-transform), A368988 (positions of records), A368989 (values of records).

Programs

PARI

A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
A344005(n) = { my(m=1); while((m*(m+1)) % n, m++); m; };
A368698(n) = A344005(A005940(1+n));

Formula

a(n) = A344005(A005940(1+n)).

For n >= 1, a(2^n) = A006093(n), a(A000225(n)) = A000225(n).