

A080709


Take sum of squares of digits of previous term, starting with 4.


14



4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37, 58, 89, 145, 42, 20, 4, 16, 37
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OFFSET

1,1


COMMENTS

Occurs as puzzle in the Nintendo DS game "Professor Layton and the Diabolical Box".  M. F. Hasler, Dec 18 2009
As the orbit of 4 under A003132, this could rather have offset 0. Merges with the orbit of 5 at the 5th term of both sequences, and with other orbits as given in the formula section.
Porges gave his "set of eight numbers" as a(1)..a(8) in this order, rather than that of the set A039943. (End)


REFERENCES

R. Honsberger, Ingenuity in Math., Random House, 1970, p. 83.


LINKS



FORMULA

Periodic with period 8.


MATHEMATICA



PROG

(Haskell)
a080709 n = a080709_list !! (n1)
a080709_list = iterate a003132 4
(Magma) &cat[[4, 16, 37, 58, 89, 145, 42, 20]: n in [0..17]]; // Vincenzo Librandi, Jan 29 2013


CROSSREFS

Cf. A003132 (the iterated map), A003621, A039943, A099645, A031176, A007770, A000216 (starting with 2), A000218 (starting with 3), A000221 (starting with 5), A008460 (starting with 6), A008462 (starting with 8), A008463 (starting with 9), A139566 (starting with 15), A122065 (starting with 74169).  M. F. Hasler, May 24 2009


KEYWORD

nonn,base,easy


AUTHOR



STATUS

approved



