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A096823 Numbers of the form p*(p+(2n-1))/2 created with smallest primes of form p=2^x-(2n-1)=A096522(n). Here the exponent equals x=A096502[n], the least exponent providing this kind of primes. Peculiarity of the present terms is as follows: Mod[sigma[a(n)],a[n]]=2*n. 0
6, 20, 12, 151115727449904501489664, 56, 40, 24, 272, 1504, 208, 176, 1312, 112, 80, 48, 6208, 992, 928, 2059264, 5696, 736, 144115176533131264, 608, 544, 5056, 416, 352, 4672, 224, 160, 96, 24704, 24448, 3904, 3776, 487936, 112384, 3392, 22912 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These numbers are clearly analogous to perfect numbers.

LINKS

Table of n, a(n) for n=1..39.

EXAMPLE

a[1]=6 is the first even perfect number;

a[7]=24 corresponds to A096821(1)=24;

a[4]=151115727449904501489664=2^38*(2^39-7)=274877906944*549755813881;

CROSSREFS

Cf. A096502, A096821, A096822.

Sequence in context: A090590 A002566 A087998 * A321328 A007253 A096897

Adjacent sequences:  A096820 A096821 A096822 * A096824 A096825 A096826

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 13 2004

STATUS

approved

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Last modified November 18 07:22 EST 2019. Contains 329252 sequences. (Running on oeis4.)