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A057719
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Prime factors of numbers in A006521 (numbers n such that n divides 2^n+1).
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5
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3, 19, 163, 571, 1459, 8803, 9137, 17497, 41113, 52489, 78787, 87211, 135433, 139483, 144667, 164617, 174763, 196579, 274081, 370009, 370387, 478243, 760267, 941489, 944803, 1041619, 1220347, 1236787, 1319323, 1465129, 1663579, 1994659
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| A prime p is in this sequence iff all prime divisors of ord_p(2)/2 are in this sequence, where ord_p(2) is the order of 2 modulo p. - Max Alekseyev (maxale(AT)gmail.com), Jul 30 2006
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LINKS
| T. D. Noe, Table of n, a(n) for n=1..100
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EXAMPLE
| 2^171+1 = 0 (mod 171), 171=3^3*19 2^13203+1 = 0 (mod 13203), 13203=3^4*163
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PROG
| (PARI) { A057719() = local(S, f); S=Set([2]); forprime(p=3, 10^7, f=factorint(znorder(Mod(2, p))); if(f[1, 1]!=2||f[1, 2]!=1, next); f=f[, 1]; if(length(setintersect(S, Set(f)))==length(f), S=setunion(S, [p]); print1(p, ", "))) }
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CROSSREFS
| Cf. A006521, A066364.
Cf. A136474, A136473.
Sequence in context: A105784 A077046 A054765 * A199559 A136474 A183069
Adjacent sequences: A057716 A057717 A057718 * A057720 A057721 A057722
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KEYWORD
| nonn
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AUTHOR
| Ignacio Larrosa Canestro (ignacio.larrosa(AT)eresmas.net) Oct 26 2000
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EXTENSIONS
| Edited by Max Alekseyev (maxale(AT)gmail.com) Jul 30 2006
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