A105604 Sylvester dividends for Jacobsthal numbers.

1, 1, 1, 1, 1, 3, 1, 5, 3, 11, 1, 105, 1, 43, 33, 85, 1, 1197, 1, 1705, 129, 683, 1, 23205, 11, 2731, 171, 27305, 1, 2370291, 1, 21845, 2049, 43691, 473, 5679765, 1, 174763, 8193, 5941925, 1, 621456339, 1, 6990505, 622611, 2796203, 1, 1437248085, 43, 346729141, 131073, 111848105, 1, 22861753173, 7513, 1521134245

Offset

1,6

Comments

Divide each Jacobsthal number by its primitive part.

Links

Antti Karttunen, Table of n, a(n) for n = 1..4096

Formula

a(n) = A001045(n)/A105603(n).

Prog

(PARI)
A001045(n) = ((2^n - ((-1)^n)) / 3);
A105603(n) = if(1==n, n, (-1)^eulerphi(n)*polcyclo(n, -2)); \\ After Wolfdieter Lang's formula in that entry.
A105604(n) = (A001045(n)/A105603(n)); \\ Antti Karttunen, Nov 01 2017

Crossrefs

Cf. A001045, A105603.

Sequence in context: A195835 A077881 A129095 * A117576 A112447 A289360

Adjacent sequences: A105601 A105602 A105603 * A105605 A105606 A105607

Keyword

easy,nonn

Author

Paul Barry, Apr 15 2005

Extensions

More terms from Antti Karttunen, Nov 01 2017

Status

approved