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A037172 Numbers n such that sigma(n) - n = {number of primes <= n}. 2
1, 2, 9, 85, 2569, 2723, 2807, 174449, 1302379, 8513821, 10518107, 14348051, 70110091, 70111621, 70112369, 10910880311, 43908943297, 4224496855063 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..18.

PROG

(PARI) isok(n) = (sigma(n)-n == primepi(n)) \\ Michel Marcus, Jul 14 2013

CROSSREFS

Sequence in context: A125797 A068595 A330475 * A106163 A278332 A135747

Adjacent sequences:  A037169 A037170 A037171 * A037173 A037174 A037175

KEYWORD

nonn,more

AUTHOR

Naohiro Nomoto

EXTENSIONS

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Apr 09 2002

a(16)-a(17) from Donovan Johnson, Sep 03 2008

a(18) from Giovanni Resta, Jul 05 2016

STATUS

approved

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Last modified April 7 15:56 EDT 2020. Contains 333306 sequences. (Running on oeis4.)