cp's OEIS Frontend

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).

%I A138819 #9 Mar 11 2014 01:34:11
%S A138819 236,478,616,478,616,616,478,478,616,616,478,478,616,478,478,478,616,
%T A138819 616,616,478,616,616,616,616,616,616,616,478,478,616,478,478,616,478,
%U A138819 616,616,616,616,616
%N 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).
%C A138819 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.
%C A138819 Also, concatenation of A138125(n), A080172(n) and A094540(n).
%C A138819 For n>1 a(n) is equal to 478 or 616, only.
%C A138819 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).
%H A138819 L. C. Noll, <a href="http://isthe.com/chongo/tech/math/prime/mersenne.html">Mersenne Prime Digits and Names</a>.
%H A138819 J. M. Pedersen, <a href="http://amicable.homepage.dk/perfect.htm">Known Perfect Numbers</a>.
%H A138819 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>.
%e A138819 ===================================================================
%e A138819 .................. SHORT TABLE OF FINAL DIGITS ...................
%e A138819 ===================================================================
%e A138819 ... Final digit of even ..... Final digit of ..... Final digit of
%e A138819 ... superperfect number ..... Mersenne prime ..... perfect number
%e A138819 ........ A061652 ............... A000668 ............. A000396
%e A138819 ===================================================================
%e A138819 n = 1 ..... (2) ................... (3) .................. (6)
%e A138819 n > 1 ..... (4) ................... (7) .................. (8)
%e A138819 n > 1 ..... (6) ................... (1) .................. (6)
%Y A138819 Cf. A000396, A000668, A019279, A061652, A080172, A094540, A138125, A138816, A138817, A138818, A138841, A138842, A138843.
%K A138819 base,nonn,less
%O A138819 1,1
%A A138819 _Omar E. Pol_, Apr 05 2008