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 A004090 Sum of digits of Fibonacci numbers. 21
 0, 1, 1, 2, 3, 5, 8, 4, 3, 7, 10, 17, 9, 8, 17, 7, 24, 22, 19, 14, 24, 20, 17, 28, 27, 19, 19, 29, 21, 23, 17, 31, 30, 34, 37, 35, 27, 35, 44, 43, 24, 31, 46, 41, 33, 29, 35, 37, 54, 55, 46, 29, 48, 41, 53, 58, 48, 52, 73, 44, 54, 53, 62, 61, 51, 67, 73, 59 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS a(n) and Fib(n) are congruent modulo 9 which implies that (a(n) mod 9) is equal to (Fib(n) mod 9) A007887(n). Thus (a(n) mod 9) is periodic with the Pisano period A001175(9) = 24. - Hieronymus Fischer, Jun 25 2007 It appears that a(n)-n stays negative for n > 5832, which explains why A020995 is finite. - T. D. Noe, Mar 19 2012 LINKS T. D. Noe, Table of n, a(n) for n = 0..10000 T. D. Noe, Plot of a(n)-n for n = 0..100000 FORMULA a(n) = Fib(n) - 9*sum{k>0, floor(Fib(n)/10^k)}. - Hieronymus Fischer, Jun 25 2007 a(n) = A007953(A000045(n)). - Reinhard Zumkeller, Nov 17 2014 MATHEMATICA Table[Plus@@IntegerDigits@(Fibonacci[n]), {n, 0, 90}] (* Vincenzo Librandi, Jun 18 2015 *) PROG (PARI) a(n)=sumdigits(fibonacci(n)) \\ Charles R Greathouse IV, Feb 03 2014 (Haskell) a004090 = a007953 . a000045 -- Reinhard Zumkeller, Nov 17 2014 (MAGMA) [&+Intseq(Fibonacci(n)): n in [0..80] ]; // Vincenzo Librandi, Jun 18 2015 CROSSREFS Cf. A000045, A030132, A007953, A246558, A261587, A068500. Sequence in context: A007887 A105472 A030132 * A104205 A267758 A166015 Adjacent sequences:  A004087 A004088 A004089 * A004091 A004092 A004093 KEYWORD nonn,base,easy AUTHOR STATUS approved

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Last modified August 18 10:55 EDT 2019. Contains 326078 sequences. (Running on oeis4.)