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 A085908 Smallest 7-smooth number beginning with n. 0
 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 112, 12, 135, 14, 15, 16, 175, 18, 192, 20, 21, 224, 2304, 24, 25, 2625, 27, 28, 294, 30, 315, 32, 336, 343, 35, 36, 375, 384, 392, 40, 4116, 42, 432, 441, 45, 4608, 4704, 48, 49, 50, 512, 525, 5376, 54, 55125, 56, 576, 588, 59049, 60 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS EXAMPLE a(23) = 2304 = 2^8*3^2 is the smallest 7-smooth number beginning with 23. (23, 230, 231, 232, ..., 239, 2301, 2302, 2303 etc. have a divisor > 10.) MATHEMATICA a[n_] := Module[{d = IntegerDigits[n], k = 1}, While[Max[FactorInteger[k][[;; , 1]]] > 7 || Length[IntegerDigits[k]] < Length[d] || IntegerDigits[k][[1 ;; Length[d]]] != d, k++]; k]; Array[a, 60] (* Amiram Eldar, Apr 30 2022 *) PROG (PARI) hc(n) = local(f); f = factor(n); f[matsize(f)[1], 1] < 10; a(n) = local(d, x); if (hc(n), return(n)); d = 1; while (d, for (i = 1, 10^d - 1, x = n*10^d + i; if (hc(x), return(x))); d++); \\ David Wasserman, Feb 11 2005 CROSSREFS Cf. A002473. Sequence in context: A258373 A250266 A357936 * A110304 A043315 A044912 Adjacent sequences: A085905 A085906 A085907 * A085909 A085910 A085911 KEYWORD base,nonn AUTHOR Amarnath Murthy, Jul 09 2003 EXTENSIONS Corrected and extended by David Wasserman, Feb 11 2005 Name corrected by J. Lowell, Apr 30 2022 STATUS approved

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Last modified March 24 18:34 EDT 2023. Contains 361510 sequences. (Running on oeis4.)