login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A092218 Primes that divide some Euler number. 6
5, 13, 17, 19, 29, 31, 37, 41, 43, 47, 53, 61, 67, 71, 73, 79, 89, 97, 101, 109, 113, 137, 139, 149, 157, 173, 181, 193, 197, 223, 229, 233, 241, 251, 257, 263, 269, 277, 281, 293, 307, 311, 313, 317, 337, 349, 353, 359, 373, 379, 389, 397, 401, 409, 419, 421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For a prime p in this sequence, p will divide an Euler number E(k) for k < p. The density of these primes is approximately 0.66.

This sequence is the union of A002144 (primes of the form 4k+1) and A120115. Note that if prime p=1 (mod 4), then p divides E(p-1). - T. D. Noe, Jun 09 2006

LINKS

T. D. Noe, Table of n, a(n) for n = 1..586

L. Carlitz, Note on irregular primes, Proc. Amer. Math. Soc. 5 (1954), 329-331

S. S. Wagstaff, Jr., Prime divisors of the Bernoulli and Euler numbers

Eric Weisstein's World of Mathematics, Euler Number

MATHEMATICA

ee=Table[Abs[EulerE[2i]], {i, 500}]; t=Table[p=Prime[n]; cnt=0; Do[If[Mod[ee[[i]], p]==0, cnt++ ], {i, p}]; cnt, {n, PrimePi[500]}]; Prime[Select[Range[Length[t]], t[[ # ]]>0&]]

CROSSREFS

Cf. A000364 (Euler numbers), A092217 (primes that do not divide any Euler number), A092219.

Sequence in context: A158334 A282747 A088908 * A049092 A103666 A082700

Adjacent sequences:  A092215 A092216 A092217 * A092219 A092220 A092221

KEYWORD

nonn

AUTHOR

T. D. Noe, Feb 25 2004

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 23 13:11 EDT 2018. Contains 316528 sequences. (Running on oeis4.)