A078931 Numbers k that divide prime(k)+1 or prime(k)-1.

1, 2, 3, 4, 5, 6, 10, 12, 14, 70, 72, 181, 182, 440, 1053, 6458, 6459, 6460, 6461, 6466, 6471, 40087, 40089, 100362, 251712, 251732, 251737, 251742, 637236, 637320, 637334, 637336, 1617173, 4124466, 10553445, 10553455, 10553504, 10553505, 10553547, 10553569

Offset

1,2

Links

Table of n, a(n) for n=1..40.

Formula

Equals A023143 union A045924.

a(n) = A000720(A162567(n)). - Alois P. Heinz, Feb 20 2023

Example

181 is in the sequence because the 181st prime is 1087, and 1086 is divisible by 181 (although 1088 is not so divisible).

Mathematica

ndpQ[n_]:=Module[{p=Prime[n]}, Divisible[p-1, n]||Divisible[p+1, n]]; Select[Range[100000], ndpQ]  (* Harvey P. Dale, Apr 03 2011 *)

Crossrefs

Cf. A000720, A162567.

Sequence in context: A333987 A342476 A285614 * A018779 A018382 A348654

Adjacent sequences: A078928 A078929 A078930 * A078932 A078933 A078934

Keyword

nonn

Author

Benoit Cloitre, Jan 12 2003

Extensions

Corrected and example added by Harvey P. Dale, Apr 03 2011

Extended with terms from A023143 and A045924 by Michel Marcus, Nov 30 2013

Status

approved