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Search: id:A070225
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| A070225 |
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Numbers n such that (sigma(n)-n) - sum(p|n,p^2) = -1. |
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+0
1
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| 4, 45, 175, 1573, 5491, 26071, 72283, 212341, 367993, 1050703, 1247941, 2608891, 3352351, 5799421, 7040833, 7722991, 11800141, 13766161, 19609831, 22345963, 30273673, 42022741, 73911181, 80434513, 98397223, 141963643, 184867531, 215639401, 235646491, 264196483
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(1)=4 a(n+1)=A001359(n)^2*(A001359(n)+2) where A001359(n) are the lesser of twin primes
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PROGRAM
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(PARI) for(n=1, 1000000, if(sumdiv(n, d, d)-n+1-sumdiv(n, d, isprime(d)*d^2)==0, print1(n, ", ")))
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CROSSREFS
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Adjacent sequences: A070222 A070223 A070224 this_sequence A070226 A070227 A070228
Sequence in context: A134174 A024254 A075029 this_sequence A132998 A120075 A123650
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KEYWORD
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easy,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), May 07 2002
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