The On-Line Encyclopedia of Integer Sequences (OEIS)

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A181561

Primes of the form highly abundant number + 1.
(history; published version)

#12 by Bruno Berselli at Fri Jun 07 04:26:54 EDT 2019

STATUS

reviewed

approved

#11 by Michel Marcus at Fri Jun 07 04:15:25 EDT 2019

STATUS

proposed

reviewed

#10 by Amiram Eldar at Fri Jun 07 03:39:32 EDT 2019

STATUS

editing

proposed

Discussion

Fri Jun 07

04:14

Michel Marcus: yes your bfile match what we find with A002093 bfile

#9 by Amiram Eldar at Fri Jun 07 03:39:26 EDT 2019

MATHEMATICA

seq = {}; smax = 0; Do[s = DivisorSigma[1, n]; If[s > smax, smax = s; If[PrimeQ[n + 1], AppendTo[seq, n + 1]]], {n, 1, 10^4}]; seq (* Amiram Eldar, Jun 07 2019 *)

#8 by Amiram Eldar at Fri Jun 07 03:36:24 EDT 2019

LINKS

Amiram Eldar, <a href="/A181561/b181561.txt">Table of n, a(n) for n = 1..1500</a>

STATUS

approved

editing

#7 by Russ Cox at Fri Mar 30 18:40:58 EDT 2012

AUTHOR

_Jonathan Vos Post (jvospost3(AT)gmail.com), _, Jan 29 2011

Discussion

Fri Mar 30

18:40

OEIS Server: https://oeis.org/edit/global/228

#6 by T. D. Noe at Sun Jan 30 14:36:29 EST 2011

STATUS

reviewed

approved

#5 by R. J. Mathar at Sun Jan 30 11:24:39 EST 2011

STATUS

proposed

reviewed

#4 by R. J. Mathar at Sun Jan 30 11:24:17 EST 2011

DATA

2, 3, 5, 7, 11, 13, 17, 19, 31, 37, 43, 61, 73, 97, 109, 181, 211, 241, 337, 421, 541, 601, 631, 661, 1009, 1201, 1621, 1801, 2161, 2341, 2521, 3121, 3361, 4201, 4621, 5881, 6121, 6301, 7561, 8821, 9241, 12241, 12601, 13441, 15121, 16381, 18481, 19801, 20161, 21841, 23761, 30241, 35281

#3 by Jonathan Vos Post at Sat Jan 29 16:22:09 EST 2011

NAME

allocated for Jonathan Vos PostPrimes of the form highly abundant number + 1.

DATA

2, 3, 5, 7, 11, 13, 17, 19, 31, 37, 43, 61, 73, 97, 109, 181, 211, 241, 337, 421, 541, 601, 631, 661, 1009, 1201, 1621, 1801

OFFSET

1,1

FORMULA

{A002093(i) + 1} INTERSECTION A000040.

{1 + (sigma(n) > sigma(m) for all m < n + 1)} INTERSECTION A000040.

EXAMPLE

The 52nd highly abundant number is 1800, add one to get 1801 which is prime.

CROSSREFS

Cf. A000040, A000203, A002093.

KEYWORD

allocated

nonn,easy

AUTHOR

Jonathan Vos Post (jvospost3(AT)gmail.com), Jan 29 2011

STATUS

approved

proposed