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A064445
Numbers k such that sopf(k) - pi(k) = tau(k).
0
5, 39, 172, 305, 1182, 1194, 2947, 8936, 24363, 24399, 24417, 64730, 174977, 482028, 9559785, 9559905, 25876016, 25876976, 70113457, 189965322, 189967014, 189967122, 189967266, 189968202, 1394198020, 3779850963, 3779851593
OFFSET
1,1
EXAMPLE
5 is in the sequence since sopf(5) - pi(5) = 5 - 3 = 2 = tau(5).
PROG
(PARI) sopf(n, fac) = fac=factor(n); sum(i=1, matsize(fac)[1], fac[i, 1]); pi(x, c) = forprime(p=2, x, c++); c for(n=1, 10^6, if(sopf(n)-pi(n)==numdiv(n), print(n)))
CROSSREFS
Cf. A000005 (tau), A000720 (pi), A008472 (sopf).
Sequence in context: A153267 A183477 A219086 * A123614 A218918 A075135
KEYWORD
nonn
AUTHOR
Jason Earls, Oct 02 2001
EXTENSIONS
More terms from Klaus Brockhaus, Oct 05 2001. No further term < 800000.
Corrected offset and a(15)-a(27) from Donovan Johnson, Mar 10 2010
STATUS
approved