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 A268583 Happycab numbers: the smallest happy number that is the sum of two cubes of happy numbers in n different ways. 1
 7859, 681179092750, 4466203788801326865111 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n)>3.6*10^24 for n >=4. This lower bound was established by exhaustive crowd computing. Upper bounds: a(4)<= 3915335521240189321820073984 =467175960^3+1562319144^3 =569783808^3+1550898288^3 =1085420968^3+1381483928^3 =1157553216^3+1332193392^3 a(5)<= 1508202165690304620654479410485250200981504 =12156471201588^3+114634141265868^3 =33798481396036^3+113692639229372^3 =64341822928208^3+107486686558048^3 =69397851840576^3+105492106344912^3 =72561474196232^3+104039736026296^3 LINKS Table of n, a(n) for n=1..3. EXAMPLE a(1) = 7859 = 10^3+19^3; a(2) = 681179092750 = 4365^3+8425^3 = 5275^3+8115^3; a(3) = 4466203788801326865111 = 6193863^3+16170804^3 = 8456292^3+15688647^3 = 9457695^3+15354846^3. CROSSREFS Cf. A011541, A007770. Sequence in context: A045277 A099498 A286208 * A045292 A115426 A206069 Adjacent sequences: A268580 A268581 A268582 * A268584 A268585 A268586 KEYWORD nonn,hard,more,bref AUTHOR Corinna Regina Böger, Feb 07 2016 STATUS approved

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Last modified September 27 01:21 EDT 2023. Contains 365669 sequences. (Running on oeis4.)