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Search: id:A086827
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| A086827 |
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Smaller member of a twin prime pair such that the sum sets a record for number of prime divisors (counted with multiplicity). |
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+0
2
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| 3, 11, 59, 71, 191, 1151, 14591, 15359, 138239, 675839, 737279, 786431, 22118399, 36175871, 63700991, 138412031, 169869311, 1321205759, 4076863487, 10871635967, 24159191039, 370440929279, 1793819934719, 2348273369087
(list; graph; listen)
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OFFSET
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0,1
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EXAMPLE
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191:193 are twin primes and 384 has 8 prime divisors; 1151:1153 are twin primes and 2304 has 10 prime divisors.
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PROGRAM
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(PARI) g(n) = isprime(n/2 - 1) && isprime(n/2 + 1); m = 0; forprime(n = 3, 10000, if (isprime(n + 2), c = bigomega(2*n + 2); if (c > m, m = c; print(n)))); while (m < 50, found = 0; for (i = m - 6, m, for (j = max(1, m - 1 - i), m + 4 - i, for (k = 2, 5, for (l = k, 15, n = 2^i*3^j*prime(k)*prime(l); if (g(n), if (!found || found > n, found = n)))))); t = log(found/2^m/3)/log(1.5); t = round(t); a = found/2^(m - t)/3; x = 0; i = 2^t; while (!x, if (bigomega(i) >= t, n = 2^(m - t)*3*i; if (g(n), x = n)); i++); m = bigomega(x); print(x/2 - 1)); (Wasserman)
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CROSSREFS
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Sequence in context: A009444 A071698 A089188 this_sequence A137690 A107007 A028342
Adjacent sequences: A086824 A086825 A086826 this_sequence A086828 A086829 A086830
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (jcearls(AT)cableone.net), Aug 07 2003
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Mar 30 2005
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