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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 Robert Israel, Table of n, a(n) for n = 1..67 Robert Israel, Maple program used to obtain b-file 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 Cf. A116112, A116302, A116308, A116310, A116316. Sequence in context: A369150 A260609 A260602 * A126816 A361623 A259061 Adjacent sequences: A116306 A116307 A116308 * A116310 A116311 A116312 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.)