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 A138125 Final digit of n-th even superperfect number A061652(n). 6
 2, 4, 6, 4, 6, 6, 4, 4, 6, 6, 4, 4, 6, 4, 4, 4, 6, 6, 6, 4, 6, 6, 6, 6, 6, 6, 6, 4, 4, 6, 4, 4, 6, 4, 6, 6, 6, 6, 6, 4, 4, 4, 6, 6, 4, 6, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also, final digit of n-th superperfect number A019279(n), if there are no odd superperfect numbers. LINKS Landon Curt Noll, Mersenne Prime Digits. FORMULA a(1)=2. For n>1, if final digit of n-th Mersenne prime A000668(n) is equal to 1 then a(n)=6, otherwise a(n)=4. EXAMPLE a(5)=6 because the 5th even superperfect number A061652(5) is 4096 and the final digit of 4096 is 6. a(34)=4 because the final digit of 34th Mersenne prime is 7. a(39)=6 because the final digit of 39th Mersenne prime is 1. ............................................................. ............... SHORT TABLE OF FINAL DIGITS ................. ............................................................. Final digit of ..... Final digit of Even ..... Final digit of Mersenne prime ..... Superperfect number ..... Perfect number A000668 ............ A061652 ................. A000396........ (3) ................ (2) ..................... (6) ........... (For n=1, only) (7) ................ (4) ..................... (8) ........... (1) ................ (6) ..................... (6) ........... CROSSREFS Cf. A000030, A000396, A000668, A077648, A019279, A061652, A135613, A135617, A138125. Sequence in context: A018841 A182043 A337937 * A098793 A083220 A085896 Adjacent sequences:  A138122 A138123 A138124 * A138126 A138127 A138128 KEYWORD base,nonn,less AUTHOR Omar E. Pol, Apr 01 2008, corrected Apr 03 2008 EXTENSIONS a(40)-a(47) from Jinyuan Wang, Mar 14 2020 STATUS approved

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Last modified June 14 10:04 EDT 2021. Contains 345025 sequences. (Running on oeis4.)