A084410 - OEIS

A084410

First column of triangle A084408.

1, 2, 5, 4, 13, 10, 31, 20, 30, 42, 61, 55, 109, 70, 88, 108, 181, 126, 277, 148, 174, 201, 397, 225, 255, 287, 318, 348, 547, 382, 733, 417, 456, 496, 535, 576, 947, 621, 666, 711, 1213, 758, 1499, 805, 858, 910, 1831, 963, 1020, 1078, 1137, 1195, 2207, 1255

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

a(n) is prime iff n is prime.

LINKS

Table of n, a(n) for n=1..54.

FORMULA

For n prime, a(n) = p(A034387(n)-n+1). For n composite, a(n) = A002808([n*(n+1)/2]-A034387(n)-n).

CROSSREFS

Cf. A084408, A084409, A084411.

Sequence in context: A111681 A073122 A277020 * A338073 A080067 A117824