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A164321 Let s(n) be the smallest number x such that the decimal representation of n appears as a substring of the decimal representations of the numbers [0...x] more than x times. 2
199991, 28263828, 371599993, 499999994, 5555555555, 6666666666, 7777777777, 8888888888, 9999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..9.

PROG

(Other) ;; This is a program in PLT Scheme, a.k.a. mzscheme

(define (count-matches re str start-pos)

(let ((m (regexp-match-positions re str start-pos)))

(if m (+ 1 (count-matches re str (+ (caar m) 1))) 0)))

(define (matches-n-in-zero-to-k fn n)

(do ((sum-so-far 1)

(k (+ n 1))

(re (regexp (format "~a" n))))

((fn sum-so-far k) k)

(when (equal? 0 (modulo k 1000000))

(display (format "~a ~a ~a\n" n k sum-so-far)))

(set! k (+ k 1))

(set! sum-so-far

(+ sum-so-far (count-matches re (format "~a" k) 0)))))

(define (s n)

(matches-n-in-zero-to-k > n))

CROSSREFS

Closely related to A163500 substituting > for = as suggested by Alexey Radul. The first term is given in the related A092175 which also generalizes the sequence for bases other than 10.

Sequence in context: A014778 A094799 A163500 * A230019 A106777 A094800

Adjacent sequences:  A164318 A164319 A164320 * A164322 A164323 A164324

KEYWORD

more,nonn,base

AUTHOR

Gregory Marton, Aug 12 2009

STATUS

approved

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Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)