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A032448 Smallest prime == -1 modulo prime(n). 3
3, 2, 19, 13, 43, 103, 67, 37, 137, 173, 61, 73, 163, 257, 281, 211, 353, 487, 401, 283, 1021, 157, 331, 1423, 193, 1009, 617, 641, 653, 677, 761, 523, 547, 277, 1489, 1811, 313, 977, 1669, 691, 1789, 1447, 4201, 1543, 787, 397, 421, 1783, 907, 457 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

It appears that a(n) <= prime(n)^2-1, where prime(n) = A000040(n) is the n-th prime; see A035095 for a related conjecture. If correct, this implies A006530(a(n)+1)=prime(n), which in turn implies that there are no duplicated values in the sequence.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

MATHEMATICA

f[n_] := Block[{p = Prime@ n}, r = p - 1; While[ !PrimeQ@ r, r += p]; r]; Array[f, 50] (* Robert G. Wilson v, Jun 20 2014 *)

PROG

(PARI) a(n) = {prn = prime(n); p = 2; while(p % prn != prn - 1, p = nextprime(p+1)); p; } \\ Michel Marcus, Aug 04 2013

(Haskell)

a032448 n = head [q | q <- a000040_list, let p = a000040 n,

                      q `mod` p == p - 1]

-- Reinhard Zumkeller, Aug 08 2013

CROSSREFS

Cf. A035095, A088732, A006530, A000040.

Sequence in context: A078073 A075568 A057026 * A066195 A090587 A094554

Adjacent sequences:  A032445 A032446 A032447 * A032449 A032450 A032451

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 25 2003

EXTENSIONS

Edited by Franklin T. Adams-Watters, Jun 21 2010

STATUS

approved

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Last modified March 28 22:27 EDT 2017. Contains 284249 sequences.