The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A349521 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A349521

Numbers k such that A348172(k) = 1.
(history; published version)

#15 by Peter Luschny at Thu Dec 16 11:51:43 EST 2021

STATUS

reviewed

approved

#14 by Michel Marcus at Tue Dec 07 04:09:00 EST 2021

STATUS

proposed

reviewed

#13 by Michael De Vlieger at Mon Dec 06 18:12:57 EST 2021

STATUS

editing

proposed

Discussion

Tue Dec 07

04:09

Michel Marcus: pour faire avancer le schmilblick ...

#12 by Michael De Vlieger at Mon Dec 06 18:12:36 EST 2021

MATHEMATICA

Block[{nn = 9, m, s}, m = 2^(2 nn); s = KeySort@ PositionIndex[Array[DivisorSigma[0, #]/# &, m]]; s = Reverse@ KeyDrop[s, TakeWhile[Keys@ s, 4/#^2 > m &]]; Position[Length /@ Array[Lookup[s, DivisorSigma[0, #]/#] &, 2^nn], 1][[All, 1]]] (* Michael De Vlieger, Dec 06 2021 *)

STATUS

proposed

editing

Discussion

Mon Dec 06

18:12

Michael De Vlieger: I agree with Michel.

#11 by Tejo Vrush at Sat Nov 20 14:07:03 EST 2021

STATUS

editing

proposed

Discussion

Sat Nov 20

14:50

Michel Marcus: De rien ...

#10 by Tejo Vrush at Sat Nov 20 14:07:01 EST 2021

DATA

4, 16, 20, 28, 32, 36, 44, 48, 52, 64, 68, 72, 76, 92, 100, 108, 112, 116, 124, 140, 144, 148, 160, 164, 172, 176, 180, 188, 192, 196, 208, 212, 216, 220, 224, 236, 240, 244, 252, 256, 260, 264, 268, 272, 284, 292, 304, 308, 316, 320, 332, 336, 340, 352, 356, 360, 364, 368, 380, 388, 396, 400

STATUS

proposed

editing

#9 by Michel Marcus at Sat Nov 20 13:32:06 EST 2021

STATUS

editing

proposed

#8 by Michel Marcus at Sat Nov 20 13:31:59 EST 2021

PROG

(PARI) isok(k) = my(q=numdiv(k)/k); sum(i=1, 4/q^2, numdiv(i)/i == q) == 1; \\ Michel Marcus, Nov 20 2021

STATUS

proposed

editing

#7 by Tejo Vrush at Sat Nov 20 12:43:53 EST 2021

STATUS

editing

proposed

Discussion

Sat Nov 20

13:30

Michel Marcus: Nearly same terms but I have 252 and I don't have 264

#6 by Tejo Vrush at Sat Nov 20 12:43:48 EST 2021

NAME

Numbers n k such that A348172(nk) = 1.

STATUS

proposed

editing