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A086827 Smaller member of a twin prime pair such that the sum sets a record for number of prime divisors (counted with multiplicity). 1
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; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..23.

EXAMPLE

191:193 are twin primes and 384 has 8 prime divisors; 1151:1153 are twin primes and 2304 has 10 prime divisors.

PROG

(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)

CROSSREFS

Sequence in context: A141776 A071698 A089188 * A308487 A164291 A137690

Adjacent sequences:  A086824 A086825 A086826 * A086828 A086829 A086830

KEYWORD

nonn

AUTHOR

Jason Earls, Aug 07 2003

EXTENSIONS

More terms from David Wasserman, Mar 30 2005

STATUS

approved

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Last modified July 4 12:18 EDT 2020. Contains 335448 sequences. (Running on oeis4.)