

A308243


Index of Eirregularity of prime(n).


1



0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 3, 1, 0, 1, 2, 2, 1, 1, 0, 1, 0, 3, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1
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OFFSET

1,59


COMMENTS

A prime p >= 5 is an Eirregular prime if there is an even integer 2*k such that 2 <= 2*k <= p3 and p divides E(2*k), where E(i) is the ith Euler number (A000364). The pair (p, 2*k) is called an Eirregular pair. The number of such pairs for a given p is called the index of Eirregularity of p (cf. Ernvall, Metsänkylä, 1978, p. 618).
In other words, a prime p is Eirregular if its index of Eirregularity is > 0, which is the case if p is a term of A092218. Otherwise, p is Eregular and is a term of A092217.


LINKS



PROG

a(n) = my(p=prime(n), e=2, i=0); while(e <= p3, if(a000364(e)%p==0, i++); e=e+2); i


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



