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 A060286 2^(p-1)*(2^p-1) where p is a prime. 4
 6, 28, 496, 8128, 2096128, 33550336, 8589869056, 137438691328, 35184367894528, 144115187807420416, 2305843008139952128, 9444732965670570950656, 2417851639228158837784576, 38685626227663735544086528 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) is the number whose binary representation is p 1's together with p-1 0's, where p is prime(n), for example: prime(3) = 5 so a(3) = 496 = 111110000 (2). - Omar E. Pol, Dec 12 2012 REFERENCES C. Stanley Ogilvy and John T. Anderson, "Excursions in Number Theory", Oxford University Press, NY, 1966 pp. 20-23. LINKS Harry J. Smith, Table of n, a(n) for n = 1..100 FORMULA For n > 1, a(2n) = 9*T(k) + 1 ; a(2n+1) = 9*T(K) + 1, where T(n) = A000217(n), k = (A121290(n) - 1)/2, K = 2*A121290(n). - Lekraj Beedassy, Sep 12 2006 a(A016027(n)) = A000396(n), assuming there are no odd perfect numbers. - Omar E. Pol, Dec 13 2012 EXAMPLE a(4) = 2^6(2^7 - 1) = 8128. MATHEMATICA Table[2^(Prime[n] - 1)(2^Prime[n] - 1), {n, 16}] (* Alonso del Arte, Dec 12 2012 *) PROG (PARI) { n=0; forprime (p=1, 542, write("b060286.txt", n++, " ", 2^(p - 1)*(2^p - 1)); ) } \\ Harry J. Smith, Jul 03 2009 CROSSREFS Cf. A000396, A006516. Sequence in context: A325637 A325654 A201186 * A000396 A152953 A066239 Adjacent sequences:  A060283 A060284 A060285 * A060287 A060288 A060289 KEYWORD nonn AUTHOR Jason Earls, Mar 23 2001 STATUS approved

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Last modified June 18 07:24 EDT 2019. Contains 324203 sequences. (Running on oeis4.)