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 A145338 a(n) is the smallest prime p where |d(p-1) - d(p+1)| = n. (d(m) = the number of divisors of m.) 1
 7, 2, 11, 197, 23, 37, 47, 401, 59, 1601, 181, 16901, 167, 3137, 179, 577, 419, 1297, 1051, 12101, 359, 739601, 1009, 4357, 1511, 50177, 719, 171610001, 839, 67601, 10657, 9096257, 1439, 240101, 3697, 145540097, 3023, 15877, 2879, 3587237, 2521 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(2n-1) = k^2 + 1, for all positive integers n, where k is some integer; k is even for n >= 2. LINKS EXAMPLE a(2)=11 because abs(d(10) - d(12)) = 2 while abs(d(p-1) - d(p+1)) < 2 for p=2,3,5 and 7. - Emeric Deutsch, Oct 11 2008 MAPLE with(numtheory); a:=proc(n) local j: for j while abs(tau(ithprime(j)-1)-tau(ithprime(j)+1)) <> n do end do: ithprime(j) end proc: seq(a(n), n=0..26); # Emeric Deutsch, Oct 11 2008 CROSSREFS Cf. A145337. Sequence in context: A147677 A090243 A216150 * A104586 A323995 A040048 Adjacent sequences:  A145335 A145336 A145337 * A145339 A145340 A145341 KEYWORD nonn AUTHOR Leroy Quet, Oct 08 2008 EXTENSIONS More terms from R. J. Mathar and Emeric Deutsch, Oct 10 2008 Extended from a(27) onwards by Ray Chandler, Oct 12 2008 STATUS approved

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Last modified February 21 04:55 EST 2020. Contains 332086 sequences. (Running on oeis4.)