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A116275
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Numbers k such that k*(k+4) gives the concatenation of two numbers m and m-2.
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6
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8872, 9009, 83352840, 99000099, 329767122286, 670232877711, 738226276371, 933006600339, 999000000999, 3779410975143113, 3872816717528065, 4250291784692548, 4278630943941865, 4372036686326817, 4749511753491300, 5250488246508697, 5627963313673180, 5721369056058132
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OFFSET
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1,1
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LINKS
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EXAMPLE
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99000099 * 99000103 = 98010199//98010197, where // denotes concatenation.
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PROG
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(Python)
from itertools import count, islice
from sympy import sqrt_mod
def A116275_gen(): # generator of terms
for j in count(0):
b = 10**j
a = b*10+1
for k in sorted(sqrt_mod(2, a, all_roots=True)):
if a*(b+3) <= k**2-2 < a*(a+2):
yield k-2
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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