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 A225608 The largest n-digit number where the first k digits are divisible by k. 1
 9, 98, 987, 9876, 98765, 987654, 9876545, 98765456, 987654564, 9876545640, 98765456405, 987606963096, 9876069630960, 98760696309604, 987606963096045, 9876062430364208, 98485872309636009, 984450645096105672, 9812523240364656789, 96685896604836004260 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS There are 25 terms in the sequence; the 25-digit number 3608528850368400786036725 is the largest number to satisfy the requirements. LINKS Shyam Sunder Gupta, Table of n, a(n) for n = 1..25 EXAMPLE There are nine one-digit numbers divisible by 1 and largest is 9 so a(1)=9. For 2 digit numbers, the second digit must be even (0,2,4,6,8) that make it divisible by 2, which gives 98 as largest to satisfy the requirement so a(2)=98. MATHEMATICA a=Table[j, {j, 9}]; r=2; t={}; While[!a == {}, n=Length[a]; nmax=Last[a]; k=1; b={}; While[!k>n, z0=a[[k]]; Do[z=10*z0+j; If[Mod[z, r]==0, b=Append[b, z]], {j, 0, 9}]; k++]; AppendTo[t, nmax]; a=b; r++]; t CROSSREFS Sequence in context: A147637 A057933 A064617 * A220490 A024115 A066557 Adjacent sequences:  A225605 A225606 A225607 * A225609 A225610 A225611 KEYWORD nonn,base,fini AUTHOR Shyam Sunder Gupta, Aug 04 2013 STATUS approved

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Last modified July 11 15:58 EDT 2020. Contains 335626 sequences. (Running on oeis4.)