The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A242383 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A242383

Lesser of consecutive primes whose average is an oblong number.
(history; published version)

#19 by Harvey P. Dale at Sun Oct 25 17:18:39 EDT 2020

STATUS

editing

approved

#18 by Harvey P. Dale at Sun Oct 25 17:18:35 EDT 2020

MATHEMATICA

Select[Partition[Prime[Range[4000]], 2, 1], OddQ[Sqrt[1+4*Mean[#]]]&][[All, 1]] (* Harvey P. Dale, Oct 25 2020 *)

STATUS

approved

editing

#17 by N. J. A. Sloane at Wed May 06 02:41:12 EDT 2020

STATUS

proposed

approved

#16 by Michel Marcus at Wed May 06 01:33:26 EDT 2020

STATUS

editing

proposed

#15 by Michel Marcus at Wed May 06 01:33:14 EDT 2020

CROSSREFS

Cf. A002378, A154634, A263676.

STATUS

proposed

editing

#14 by Amiram Eldar at Wed May 06 01:28:52 EDT 2020

STATUS

editing

proposed

#13 by Amiram Eldar at Wed May 06 01:23:19 EDT 2020

CROSSREFS

Cf. A154634, A263676.

#12 by Amiram Eldar at Wed May 06 01:22:24 EDT 2020

MATHEMATICA

f[n_] := NextPrime[n*(n + 1), -1] ; f /@ Select[Range[200], (ob = #*(# + 1)) == (NextPrime[ob, -1] + NextPrime[ob])/2 &] (* Amiram Eldar, May 06 2020 *)

#11 by Amiram Eldar at Wed May 06 01:22:13 EDT 2020

LINKS

Amiram Eldar, <a href="/A242383/b242383.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#10 by Alois P. Heinz at Fri Jan 04 18:32:07 EST 2019

STATUS

proposed

approved