The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A363359 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A363359

Sum of divisors of 4*n-1 of form 4*k+3.
(history; published version)

#16 by Michael De Vlieger at Sat Jul 08 08:04:59 EDT 2023

STATUS

reviewed

approved

#15 by Joerg Arndt at Sat Jul 08 05:43:16 EDT 2023

STATUS

proposed

reviewed

#14 by Amiram Eldar at Sat Jul 08 04:43:43 EDT 2023

STATUS

editing

proposed

#13 by Amiram Eldar at Sat Jul 08 04:43:41 EDT 2023

MATHEMATICA

a[n_] := DivisorSum[4*n - 1, # &, Mod[#, 4] == 3 &]; Array[a, 100] (* Amiram Eldar, Jul 08 2023 *)

STATUS

proposed

editing

#12 by Seiichi Manyama at Sat Jul 08 04:14:50 EDT 2023

STATUS

editing

proposed

#11 by Seiichi Manyama at Sat Jul 08 02:23:54 EDT 2023

DATA

3, 7, 11, 18, 19, 23, 30, 31, 42, 42, 43, 47, 54, 66, 59, 73, 67, 71, 93, 79, 83, 90, 98, 114, 113, 103, 107, 114, 138, 126, 126, 127, 131, 180, 139, 154, 157, 151, 186, 162, 163, 167, 193, 217, 179, 186, 198, 191, 252, 199, 210, 233, 211, 258, 222, 223, 227, 252, 282, 239, 273, 266, 251, 324, 266, 263, 270

#10 by Seiichi Manyama at Sat Jul 08 02:23:09 EDT 2023

FORMULA

G.f.: Sum_{k>0} (4*k-1) * x^k / (1 - x^(4*k-1)).

#9 by Seiichi Manyama at Sat Jul 08 02:20:45 EDT 2023

CROSSREFS

Cf. A050452, A078703, A364085.

#8 by Seiichi Manyama at Sat Jul 08 02:17:14 EDT 2023

PROG

(PARI) a(n) = sumdiv(4*n-1, d, (d%4==3)*d);

#7 by Seiichi Manyama at Sat Jul 08 02:03:49 EDT 2023

CROSSREFS

Cf. A050452, A078703.