A379014 Least number k such that prime(n) + prime(k) is a multiple of n, or -1 if no such number exists.

1, 2, 4, 3, 8, 3, 5, 3, 6, 5, 1, 5, 5, 6, 6, 5, 14, 5, 15, 10, 5, 11, 26, 4, 2, 2, 3, 3, 4, 4, 17, 10, 18, 11, 18, 10, 34, 27, 19, 19, 19, 10, 19, 20, 21, 11, 20, 7, 19, 20, 21, 21, 111, 8, 21, 7, 21, 8, 65, 8, 23, 7, 20, 21, 68, 6, 20, 2, 19, 20, 1, 21, 20, 20

Offset

1,2

Comments

Indices n where a(n)=1 correspond with terms of A092044. - Bill McEachen, Dec 21 2024

Links

Table of n, a(n) for n=1..74.

Formula

a(n) = A000720(A294639(n)). - Pontus von Brömssen, Dec 13 2024

Mathematica

a[n_]:=Module[{k=1}, While[!Divisible[Prime[n]+Prime[k], n], k++]; k]; Array[a, 74] (* Stefano Spezia, Dec 13 2024 *)

Prog

(PARI) a(n) = my(k=1, p=prime(n)); while ((p+prime(k)) % n, k++); k; \\ Michel Marcus, Dec 13 2024

Crossrefs

Cf. A000040, A000720, A068901, A294639.

Sequence in context: A253792 A058330 A124256 * A108503 A331595 A347288

Adjacent sequences: A379011 A379012 A379013 * A379015 A379016 A379017

Keyword

nonn

Author

Jean-Marc Rebert, Dec 13 2024

Status

approved