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A226159 a(n) = -prime(n) if prime(n) is a irregular prime else prime(n). 0
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, -37, 41, 43, 47, 53, -59, 61, -67, 71, 73, 79, 83, 89, 97, -101, -103, 107, 109, 113, 127, -131, 137, 139, -149, 151, -157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, -233, 239, 241, 251, -257, -263 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..56.

MATHEMATICA

regularQ[p_] := And @@ ( !Divisible[ Numerator[ BernoulliB[#]], p] &  /@ Range[2, p - 3, 2]); Table[p = Prime[n]; If[ regularQ[p], p, -p], {n, 1, 56}] (* Jean-Fran├žois Alcover, Jul 02 2013 *)

PROG

(Sage)

def A226159_list(len):

    t = [0]*(len+1); t[0] = 1; L = [2]; p = 1

    for m in (1..len):

        q = m + 1; t[m] = 1 / q

        for j in range(m, 0, -1) :

            t[j - 1] = (t[j - 1] - t[j]) * j

        if 2.divides(m):

            if q.divides(denominator(t[0])):

                if q.divides(p): q = -q

                L.append(q)

            p *= numerator(t[0])

    return L

A226159_list(263)

CROSSREFS

Cf. A000040, A000928.

Sequence in context: A322394 A295425 A158611 * A182986 A000040 A008578

Adjacent sequences:  A226156 A226157 A226158 * A226160 A226161 A226162

KEYWORD

sign

AUTHOR

Peter Luschny, Jun 27 2013

STATUS

approved

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Last modified February 26 11:15 EST 2021. Contains 341631 sequences. (Running on oeis4.)