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A316263 Numbers k that are a substring of k*(k-1). 3
2, 11, 50, 52, 69, 101, 250, 252, 500, 502, 685, 750, 752, 1001, 1250, 3136, 3752, 5000, 5002, 6250, 8752, 10001, 18752, 31250, 46329, 50000, 50002, 68752, 81250, 84168, 100001, 218752, 281250, 297540, 500000, 500002, 718752, 749500, 781250, 1000001, 1638694, 2914261 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Any number of the forms 10^m+1, 5*10^m and 5*10^m+2 (m>0) are part of the sequence.

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..93

EXAMPLE

69 * 68 = 4692;

8752 * 8751 = 76588752.

MAPLE

P:=proc(q) local k, n; for n from 1 to q do

for k from 1 to ilog10(n*(n-1))-ilog10(n)+1 do

if n=trunc(n*(n-1)/10^(k-1)) mod 10^(ilog10(n)+1) then print(n);

break; fi; od; od; end: P(10^8);

CROSSREFS

Cf. A305670.

Sequence in context: A036996 A262296 A151314 * A187000 A154415 A108851

Adjacent sequences:  A316260 A316261 A316262 * A316264 A316265 A316266

KEYWORD

nonn,base,easy

AUTHOR

Paolo P. Lava, Jun 28 2018

STATUS

approved

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Last modified September 18 18:27 EDT 2019. Contains 327179 sequences. (Running on oeis4.)