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A064518 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. 2
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; text; internal format)
OFFSET

1,2

COMMENTS

It is not difficult to show that these numbers have the form a(n) =3^i*4^j with j <= i <= 2j.

LINKS

Harry J. Smith, Table of n, a(n) for n = 1..50

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)) ) } \\ Harry J. Smith, Sep 17 2009

CROSSREFS

Every term is also a term of A064476.

Sequence in context: A073403 A191817 A270840 * A238923 A135178 A278583

Adjacent sequences:  A064515 A064516 A064517 * A064519 A064520 A064521

KEYWORD

nonn

AUTHOR

Vladeta Jovovic, Oct 07 2001

STATUS

approved

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Last modified May 24 00:38 EDT 2019. Contains 323528 sequences. (Running on oeis4.)