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Search: id:A064439
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| A064439 |
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Numbers n such that sigma(n)-n-1 = pi(n). |
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+0
1
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| 4, 55, 65, 95, 125, 145, 155, 185, 205, 2779, 2863, 55297, 174691, 174779, 487903, 1301989, 1302457
(list; graph; listen)
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OFFSET
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1,1
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PROGRAM
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(PARI) sig(n) = sigma(n)-n-1; pi(x, c=0) = forprime(p=2, x, c++); c for(n=1, 10^8, if(sig(n)==pi(n), print(n)))
(PARI) { n=0; for (m=1, 10^9, if ((sigma(m) - m - 1)==primepi(m), write("b064439.txt", n++, " ", m); if (n==100, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 14 2009]
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CROSSREFS
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Cf. A000720, A048050.
Sequence in context: A140604 A048371 A077658 this_sequence A133218 A151576 A073352
Adjacent sequences: A064436 A064437 A064438 this_sequence A064440 A064441 A064442
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KEYWORD
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nonn
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AUTHOR
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Jason Earls (zevi_35711(AT)yahoo.com), Oct 01 2001
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EXTENSIONS
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More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 05 2001. No further term < 800000.
a(16) - a(17) from Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 14 2009
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