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A138819 Concatenation of final digit of n-th even superperfect number A061652(n), final digit of n-th Mersenne prime A000668(n) and final digit of n-th perfect number A000396(n). 5
236, 478, 616, 478, 616, 616, 478, 478, 616, 616, 478, 478, 616, 478, 478, 478, 616, 616, 616, 478, 616, 616, 616, 616, 616, 616, 616, 478, 478, 616, 478, 478, 616, 478, 616, 616, 616, 616, 616 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also, concatenation of final digit of n-th superperfect number A019279(n), final digit of n-th Mersenne prime A000668(n) and final digit of n-th perfect number A000396(n), if there are no odd superperfect numbers.

Also, concatenation of A138125(n), A080172(n) and A094540(n).

For n>1 a(n) is equal to 478 or 616, only.

Note that, for n>1: if the final digit of n-th Mersenne prime A000668(n) is 1 then the final digit of n-th even superperfect number is 6 and the final digit of n-th perfect number also is 6, otherwise the final digit of n-th even superperfect number is 4 and the final digit of n-th perfect number is 8 (see example).

LINKS

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

L. C. Noll, Mersenne Prime Digits and Names.

J. M. Pedersen, Known Perfect Numbers.

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

EXAMPLE

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

.................. SHORT TABLE OF FINAL DIGITS ...................

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

... Final digit of even ..... Final digit of ..... Final digit of

... superperfect number ..... Mersenne prime ..... perfect number

........ A061652 ............... A000668 ............. A000396

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

n = 1 ..... (2) ................... (3) .................. (6)

n > 1 ..... (4) ................... (7) .................. (8)

n > 1 ..... (6) ................... (1) .................. (6)

CROSSREFS

Cf. A000396, A000668, A019279, A061652, A080172, A094540, A138125, A138816, A138817, A138818, A138841, A138842, A138843.

Sequence in context: A218054 A235286 A138818 * A273181 A259639 A334649

Adjacent sequences:  A138816 A138817 A138818 * A138820 A138821 A138822

KEYWORD

base,nonn,less

AUTHOR

Omar E. Pol, Apr 05 2008

STATUS

approved

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Last modified October 20 03:04 EDT 2021. Contains 348099 sequences. (Running on oeis4.)