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A138838 Concatenation of initial and final digits of n-th even superperfect number A061652(n), divided by 2. 1

%I #5 Mar 14 2020 05:56:47

%S 11,22,8,32,23,33,12,7,8,18,42,42,18,12,27,37,13,8,48,7,13,8,8,13,13,

%T 13,23,12,12,13,17,42,33,12,23,18,33,13,23,32,7,32,8,33,7,43,8

%N Concatenation of initial and final digits of n-th even superperfect number A061652(n), divided by 2.

%C Also, concatenation of initial and final digits of n-th superperfect number A019279(n), divided by 2, if there are no odd superperfect numbers.

%C Also, concatenation of A138124(n) and A138125(n), divided by 2.

%F a(n) = A138842(n)/2. - _Jinyuan Wang_, Mar 14 2020

%e a(5)=23 because the 5th even superperfect number A061652(5) is 4096 and the concatenation of initial and final digits of 4096 is 46 and 46/2 = 23.

%Y Cf. A019279, A061652, A073729, A138124, A138125, A138842.

%K nonn,base,more

%O 1,1

%A _Omar E. Pol_, Apr 02 2008

%E More terms from _Jinyuan Wang_, Mar 14 2020

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Last modified August 29 09:35 EDT 2024. Contains 375511 sequences. (Running on oeis4.)