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 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

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