A366799 Number of divisors d of n that are not of the form 4k+2, as permuted by the Doudna sequence.

1, 1, 2, 2, 2, 2, 3, 3, 2, 2, 4, 4, 3, 3, 4, 4, 2, 2, 4, 4, 4, 4, 6, 6, 3, 3, 6, 6, 4, 4, 5, 5, 2, 2, 4, 4, 4, 4, 6, 6, 4, 4, 8, 8, 6, 6, 8, 8, 3, 3, 6, 6, 6, 6, 9, 9, 4, 4, 8, 8, 5, 5, 6, 6, 2, 2, 4, 4, 4, 4, 6, 6, 4, 4, 8, 8, 6, 6, 8, 8, 4, 4, 8, 8, 8, 8, 12, 12, 6, 6, 12, 12, 8, 8, 10, 10, 3, 3, 6, 6, 6, 6, 9, 9

Offset

0,3

Links

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

Index entries for sequences related to binary expansion of n

Formula

a(n) = A320111(A005940(1+n)).

Prog

(PARI)
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
A320111(n) = sumdiv(n, d, (2!=(d%4)));
A366799(n) = A320111(A005940(1+n));

Crossrefs

Cf. A005940, A320111, A366800 (rgs-transform).

Cf. also A366797.

Sequence in context: A247069 A367008 A366800 * A322168 A118377 A023516

Adjacent sequences: A366796 A366797 A366798 * A366800 A366801 A366802

Keyword

nonn

Author

Antti Karttunen, Oct 27 2023

Status

approved