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A138882 Triangle read by rows: row n lists divisors of n-th even superperfect number A061652(n). 2
1, 2, 1, 2, 4, 1, 2, 4, 8, 16, 1, 2, 4, 8, 16, 32, 64, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The number of divisors of n-th even superperfect number is equal to A000043(n), then row n has A000043(n) terms.

The sum of divisors of n-th even superperfect number is equal to n-th Mersenne prime A000668(n), then n-th row sum is equal to A000668(n).

LINKS

Table of n, a(n) for n=1..62.

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos".

EXAMPLE

Triangle begins:

1, 2

1, 2, 4

1, 2, 4, 8, 16

1, 2, 4, 8, 16, 32, 64

1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096

==============================================================

..... Mersenne ..............................................

....... prime ...............................................

n ... A000668(n) = Sum of divisors of A061652(n) .............

==============================================================

1 ........ 3 ... = 1+2

2 ........ 7 ... = 1+2+4

3 ....... 31 ... = 1+2+4+8+16

4 ...... 127 ... = 1+2+4+8+16+32+64

5 ..... 8191 ... = 1+2+4+8+16+32+64+128+256+512+1024+2048+4096

CROSSREFS

Cf. A000005, A000043, A000203, A000668, A019279, A061652, A133031.

Sequence in context: A300653 A256009 A123937 * A074634 A152036 A035015

Adjacent sequences:  A138879 A138880 A138881 * A138883 A138884 A138885

KEYWORD

nonn,tabf

AUTHOR

Omar E. Pol, Apr 11 2008

STATUS

approved

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Last modified May 28 12:02 EDT 2020. Contains 334681 sequences. (Running on oeis4.)