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A064518
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For an integer n with prime factorization p_1*p_2*p_3* ... *p_m let n* =(p_1+1)*(p_2+1)*(p_3+1)* ... *(p_m+1); sequence gives n* such that n* is divisible by n.
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2
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1, 12, 36, 144, 432, 1296, 1728, 5184, 15552, 20736, 46656, 62208, 186624, 248832, 559872, 746496, 1679616, 2239488, 2985984, 6718464, 8957952, 20155392, 26873856, 60466176, 35831808, 80621568, 107495424, 241864704, 322486272
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| It is not difficult to show that these numbers have the form a(n) =3^i*4^j with j <= i <= 2j.
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,50
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PROG
| (PARI) ns(n)= { local(f, p=1); f=factor(n); for(i=1, matsize(f)[1], p*=(1 + f[i, 1])^f[i, 2]); return(p) } { n=0; for (m=1, 10^9, s=ns(m); if (s%m == 0, write("b064518.txt", n++, " ", s); if (n==50, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 17 2009]
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CROSSREFS
| Every term is also a term of A064476.
Sequence in context: A058880 A055551 A073403 * A135178 A085331 A058040
Adjacent sequences: A064515 A064516 A064517 * A064519 A064520 A064521
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KEYWORD
| nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Oct 07 2001
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