A068901 Least number that when added to the n-th prime gives a multiple of n.

0, 1, 1, 1, 4, 5, 4, 5, 4, 1, 2, 11, 11, 13, 13, 11, 9, 11, 9, 9, 11, 9, 9, 7, 3, 3, 5, 5, 7, 7, 28, 29, 28, 31, 26, 29, 28, 27, 28, 27, 26, 29, 24, 27, 28, 31, 24, 17, 18, 21, 22, 21, 24, 19, 18, 17, 16, 19, 18, 19, 22, 17, 8, 9, 12, 13, 4, 3, 67, 1

Offset

1,5

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Formula

a(n) = Min_{k | n divides (prime(n)+k)}.

a(n) = A068902(n) - A000040(n).

a(n) = n*ceiling(prime(n)/n) - prime(n). - Vladeta Jovovic, Apr 06 2003

Mathematica

f[n_] := Module[{p=Prime[n]}, n*Ceiling[p/n]-p]; Array[f, 100]  (* Harvey P. Dale, Apr 06 2011 *)

Prog

(Haskell)
a068901 n = head $
   filter ((== 0) . (`mod` fromIntegral n) . (+ a000040 n)) $ [0..]
-- Reinhard Zumkeller, Feb 18 2012

Crossrefs

Cf. A090973. - Reinhard Zumkeller, Aug 16 2009

Cf. A000040, A068902.

Sequence in context: A343954 A063694 A242624 * A010710 A021026 A126128

Adjacent sequences: A068898 A068899 A068900 * A068902 A068903 A068904

Keyword

nonn,nice,look

Author

Reinhard Zumkeller, Mar 05 2002

Status

approved