A138838 - OEIS

A138838

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

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

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OFFSET

1,1

COMMENTS

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

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

LINKS

Table of n, a(n) for n=1..47.

FORMULA

a(n) = A138842(n)/2. - Jinyuan Wang, Mar 14 2020

EXAMPLE

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.

CROSSREFS

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

Sequence in context: A257491 A169853 A064263 * A139337 A231115 A040110

Adjacent sequences: A138835 A138836 A138837 * A138839 A138840 A138841

KEYWORD

nonn,base,more

AUTHOR

Omar E. Pol, Apr 02 2008

EXTENSIONS

More terms from Jinyuan Wang, Mar 14 2020

STATUS

approved