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A234315 Let x(0)x(1)x(2)... x(q) denote the decimal expansion of n. Sequence lists the numbers n such that the suffix of decimal expansion x(2)... x(q) is the p-th divisor of n where p is the prefix of decimal expansion x(0)x(1). 1

%I

%S 1280,1872,10020,10050,12040,12500,14200,17200,19250,24150,42336,

%T 46920,100020,100032,100125,110176,120160,120200,141250,170040,180300,

%U 190152,200800,220200,220880,222500,230100,240640,251250,260100,262000,270180,270750,291450

%N Let x(0)x(1)x(2)... x(q) denote the decimal expansion of n. Sequence lists the numbers n such that the suffix of decimal expansion x(2)... x(q) is the p-th divisor of n where p is the prefix of decimal expansion x(0)x(1).

%e 1872 is in the sequence because the divisors of 1872 are {1, 2, 3, 4, 6, 8, 9, 12, 13, 16, 18, 24, 26, 36, 39, 48, 52, 72, 78, 104, 117, 144, 156, 208, 234, 312, 468, 624, 936, 1872} and 72 is the 18th divisor of 1872.

%p with(numtheory):for n from 1000 to 500000 do:x:=convert(n,base,10):n1:=nops(x):y:=divisors(n):n2:=nops(y):a:=x[n1]*10+x[n1-1]: s:=sum('x[i]*10^(i-1) ', 'i'=1..n1-2):if n2>a and y[a]=s then printf(`%d, `,n):else fi:od:

%Y Cf. A234314.

%K nonn,base

%O 1,1

%A _Michel Lagneau_, Dec 23 2013

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Last modified January 25 16:42 EST 2020. Contains 331245 sequences. (Running on oeis4.)