The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A039915 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A039915

Smallest k such that k(p-1)-1 is positive and divisible by p where p = n-th prime.
(history; published version)

#21 by N. J. A. Sloane at Fri Oct 30 20:33:20 EDT 2015

STATUS

editing

approved

#20 by N. J. A. Sloane at Fri Oct 30 20:33:17 EDT 2015

CROSSREFS

Cf. A000217, A039678. Essentially the same as A006093.

Essentially the same as A006093.

KEYWORD

nice,nonn

nonn

STATUS

approved

editing

#19 by N. J. A. Sloane at Sat May 18 16:49:22 EDT 2013

AUTHOR

Felice Russo (frusso(AT)micron.com)

Felice Russo

Discussion

Sat May 18

16:49

OEIS Server: https://oeis.org/edit/global/1921

#18 by Joerg Arndt at Wed Dec 26 11:30:09 EST 2012

STATUS

proposed

approved

#17 by Jean-François Alcover at Wed Dec 26 04:17:18 EST 2012

STATUS

editing

proposed

#16 by Jean-François Alcover at Wed Dec 26 04:17:10 EST 2012

MATHEMATICA

a[n_] := Prime[n]-1; a[1]=3; Table[a[n], {n, 1, 58}] (* Jean-François Alcover, Dec 26 2012, after Juri-Stepan Gerasimov *)

STATUS

approved

editing

#15 by Harvey P. Dale at Tue Jun 12 09:12:42 EDT 2012

STATUS

editing

approved

#14 by Harvey P. Dale at Tue Jun 12 09:12:18 EDT 2012

MATHEMATICA

kp[n_]:=Module[{p=Prime[n], k=1}, While[!Divisible[(k(k+1))/2, p], k++]; k]; Array[kp, 60] (* Harvey P. Dale, Jun 12 2012 *)

STATUS

approved

editing

#13 by Russ Cox at Fri Mar 30 18:52:24 EDT 2012

FORMULA

a(n) = p+(-1)^p. - _Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), _, May 26 2009

Discussion

Fri Mar 30

18:52

OEIS Server: https://oeis.org/edit/global/257

#12 by Russ Cox at Fri Mar 30 18:50:12 EDT 2012

COMMENTS

Also smallest positive k such that the k-th triangular number is divisible by the n-th prime. - _Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), _, Apr 19 2002

Discussion

Fri Mar 30

18:50

OEIS Server: https://oeis.org/edit/global/246