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A048572 a(n) = sum of digits of a(n-1)*a(n-2). 1
1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2, 1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2, 1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This sequence is periodic with period 24. - T. D. Noe, Feb 15 2008

LINKS

Table of n, a(n) for n=1..72.

Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).

FORMULA

a(n)=(1/6624)*{439*(n mod 24)+991*[(n+1) mod 24]-113*[(n+2) mod 24]+1267*[(n+3) mod 24]+1819*[(n+4) mod 24]+715*[(n+5) mod 24]-1217*[(n+6) mod 24]-665*[(n+7) mod 24]-113*[(n+8) mod 24]-389*[(n+9) mod 24]+163*[(n+10) mod 24]+1543*[(n+11) mod 24]+1267*[(n+12) mod 24]-665*[(n+13) mod 24]-941*[(n+14) mod 24]+439*[(n+15) mod 24]-1493*[(n+16) mod 24]+715*[(n+17) mod 24]+439*[(n+18) mod 24]+991*[(n+19) mod 24]-941*[(n+20) mod 24]-389*[(n+21) mod 24]+163*[(n+22) mod 24]-113*[(n+23) mod 24]}, with n>=0 [From Paolo P. Lava, Apr 01 2009]

MATHEMATICA

Nest[Append[#, Total[IntegerDigits[Last[#]#[[-2]]]]]&, {1, 2}, 80]  (* Harvey P. Dale, Apr 21 2011 *)

PadRight[{}, 100, {1, 2, 2, 4, 8, 5, 4, 2, 8, 7, 11, 14, 10, 5, 5, 7, 8, 11, 16, 14, 8, 4, 5, 2}] (* Harvey P. Dale, Jan 18 2015 *)

CROSSREFS

Sequence in context: A077964 A077968 A123958 * A121173 A160159 A283241

Adjacent sequences:  A048569 A048570 A048571 * A048573 A048574 A048575

KEYWORD

nonn,easy,nice,base

AUTHOR

David Johnson-Davies

STATUS

approved

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Last modified February 15 21:12 EST 2019. Contains 320138 sequences. (Running on oeis4.)