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 A306509 a(n) is the number of divisors of the sum of digits of n. 1
 1, 2, 2, 3, 2, 4, 2, 4, 3, 1, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 2, 3, 2, 4, 2, 4, 3, 4, 2, 6, 3, 2, 4, 2, 4, 3, 4, 2, 6, 2, 2, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 2, 4, 3, 4, 2, 6, 2, 4, 4, 5, 4, 3, 4, 2, 6, 2, 4, 4, 5, 2, 3, 4, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n) = A000005(A007953(n)). a(10*n) = a(n). - Rémy Sigrist, Feb 25 2019 EXAMPLE a(17) = A000005(A007953(17)) = A000005(8) = 4. PROG (PARI) a(n) = numdiv(sumdigits(n)); \\ Michel Marcus, Feb 20 2019 CROSSREFS Cf. A000005, A007953. Sequence in context: A327391 A083903 A327536 * A083867 A076888 A087990 Adjacent sequences:  A306506 A306507 A306508 * A306510 A306511 A306512 KEYWORD nonn,base AUTHOR Ctibor O. Zizka, Feb 20 2019 STATUS approved

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Last modified January 23 13:52 EST 2020. Contains 331171 sequences. (Running on oeis4.)