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 A328309 a(n) counts the numbers in 0..n whose k-th arithmetic derivative is zero for some k >= 0. 4
 1, 2, 3, 4, 4, 5, 6, 7, 7, 8, 9, 10, 10, 11, 12, 12, 12, 13, 14, 15, 15, 16, 17, 18, 18, 19, 19, 19, 19, 20, 21, 22, 22, 23, 24, 24, 24, 25, 26, 26, 26, 27, 28, 29, 29, 29, 30, 31, 31, 32, 32, 32, 32, 33, 33, 33, 33, 34, 35, 36, 36, 37, 38, 38, 38, 39, 40, 41, 41, 41, 42, 43, 43, 44, 44, 44, 44, 45, 46, 47, 47, 47, 48 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n) is the number of terms m in A099308 such that m <= n. LINKS Antti Karttunen, Table of n, a(n) for n = 0..65537 FORMULA a(0) = 1; for n > 0, a(n) = a(n-1) + A328308(n). For all n >= 0, a(A099308(n)) = n. PROG (PARI) up_to = 65537; A003415checked(n) = if(n<=1, 0, my(f=factor(n), s=0); for(i=1, #f~, if(f[i, 2]>=f[i, 1], return(0), s += f[i, 2]/f[i, 1])); (n*s)); A328308(n) = if(!n, 1, while(n>1, n = A003415checked(n)); (n)); A328309list(up_to) = { my(v=vector(up_to), s=A328308(0)); for(i=1, up_to, s += A328308(i); v[i] = s); (v); }; v328309 = A328309list(up_to); A328309(n) = if(!n, 1, v328309[n]); CROSSREFS Cf. A003415. Partial sums of A328308. A left inverse of A099308. Cf. also A328307. Sequence in context: A255338 A123580 A072894 * A037915 A195180 A069210 Adjacent sequences:  A328306 A328307 A328308 * A328310 A328311 A328312 KEYWORD nonn AUTHOR Antti Karttunen, Oct 12 2019 STATUS approved

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Last modified August 8 10:26 EDT 2022. Contains 356009 sequences. (Running on oeis4.)