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A031157 Numbers that are both lucky and prime. 22
3, 7, 13, 31, 37, 43, 67, 73, 79, 127, 151, 163, 193, 211, 223, 241, 283, 307, 331, 349, 367, 409, 421, 433, 463, 487, 541, 577, 601, 613, 619, 631, 643, 673, 727, 739, 769, 787, 823, 883, 937, 991, 997, 1009, 1021, 1039, 1087, 1093, 1117, 1123 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
A010051(a(n))*A145649(a(n)) = 1. -Reinhard Zumkeller,Oct 19 2008
Conjecture: This sequence is infinite. -Ahmad J. Masad,Feb 17 2020
Conjecture: If this sequence is infinite, then there exists a minimum sufficiently large integer k, such that for all a(n) > k, there exists a positive integer x and there exists m>n such that x(x-1) < a(n) < x^2 and x^2 < a(m) < x(x+1). This conjecture is similar to Oppermann's conjecture. -Ahmad J. Masad,Jun 23 2020
LINKS
Wikipedia,Lucky prime
MATHEMATICA
luckies = Range[1, 1248, 2]; i = 2; While[ i <= (len = Length@luckies) && (k = luckies[[i]]) <= len, luckies = Drop[luckies, {k, len, k}]; i++ ]; Select[luckies, PrimeQ@# &] (*Robert G. Wilson v,May 12 2006 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified July 19 16:24 EDT 2024. Contains 374410 sequences. (Running on oeis4.)