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A116309 Numbers k such that k*(k+3) gives the concatenation of two numbers m and m+3. 6
40, 58, 32262232, 67737766, 79321056, 3341093417798787499093, 3861488851737861033961, 4747922651210186579787, 5252077348789813420211, 6138511148262138966037, 6658906582201212500905, 7232275368591793618231 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
79321056 * 79321059 = 62918301//62918304, where // denotes concatenation.
MAPLE
As:= {}:
for m from 2 to 62 do
acands:= map(t -> rhs(op(t)), [msolve(a*(a+3)=3, 10^m+1)]);
bcands:= map(t -> t*(t+3) mod 10^m, acands);
good:= select(t -> bcands[t]>=10^(m-1), [$1..nops(acands)]);
As:= As union convert(acands[good], set);
od:
sort(convert(As, list)); # Robert Israel, Aug 20 2019
CROSSREFS
Sequence in context: A369150 A260609 A260602 * A126816 A361623 A259061
KEYWORD
nonn,base
AUTHOR
Giovanni Resta, Feb 06 2006
STATUS
approved

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Last modified June 24 00:02 EDT 2024. Contains 373661 sequences. (Running on oeis4.)