Search: id:A061645
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%I A061645
%S A061645 4,6,10,14,26,34,38,62,122,178,214,254,1042,1214,2558,4406,4562,6434,
%T A061645 8506,8846,19378,19882,22426,39874,43402,46418,88994,172486,221006,
%U A061645 264098,432182,1513678,1718866,2515574,2796538,5952442,6042754
%N A061645 a(n) = number of divisors of n-th perfect number.
%C A061645 The number of divisors of n-th perfect number that are powers of 2 is 
               equal to a(n)/2, assuming there are no odd perfect numbers. The number 
               of divisors of n-th perfect number that are multiples of n-th Mersenne 
               prime A000668(n) is also equal to a(n)/2, assuming there are no odd 
               perfect numbers. (See A000043). - Omar E. Pol (info(AT)polprimos.com), 
               Feb 28 2008
%H A061645 O. E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica 
               de los numeros primos y perfectos</a>.
%F A061645 a(n) = A000005[A000396(n)] = 2*A000043(n)
%F A061645 a(n) = floor{log_2(A000396(n))} + 2. - Lekraj Beedassy (blekraj(AT)yahoo.com), 
               Aug 21 2004
%e A061645 8128 = 2*2*2*2*2*2*127 with 14 divisors.
%Y A061645 Cf. A000005, A000396, A000043.
%Y A061645 Cf. A000668.
%Y A061645 Sequence in context: A049632 A061227 A000066 this_sequence A084372 A140611 
               A076957
%Y A061645 Adjacent sequences: A061642 A061643 A061644 this_sequence A061646 A061647 
               A061648
%K A061645 easy,nonn
%O A061645 1,1
%A A061645 Labos E. (labos(AT)ana.sote.hu), Jun 14 2001

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