A268757 Unhappycab numbers: the smallest unhappy number that is the sum of two cubes of unhappy numbers in n different ways.

16, 4104, 119824488, 74213505639000, 6123582409620312000

Offset

1,1

Comments

a(6) <= 802780294845778147551744 = 9851898^3+92902278^3 = 27391106^3+92139262^3 = 52144168^3+87109808^3 = 56241696^3+85493352^3 = 58805572^3+84316316^3 = 72408488^3+75075088^3.

Links

Table of n, a(n) for n=1..5.

Formula

a(n) >= A011541(n) for n > 0. It is conjectured that there is no equality.

Example

a(1) = 16 = 2^3+2^3;
a(2) = 4104 = 2^3+16^3 = 9^3+15^3;
a(3) = 119824488 = 11^3+493^3 = 90^3+492^3 = 346^3+428^3;
a(4) = 74213505639000 = 5895^3+41985^3 = 20392^3+40358^3 = 20880^3+40230^3 = 32790^3+33900^3;
a(5) = 6123582409620312000 = 193935^3+1828785^3 = 539195^3+1813765^3 = 1026460^3+1714760^3 = 1107120^3+1682940^3 = 1157590^3+1659770^3.

Crossrefs

Cf. A011541, A031177, A268583.

Sequence in context: A053765 A193134 A139296 * A272358 A176369 A090045

Adjacent sequences: A268754 A268755 A268756 * A268758 A268759 A268760

Keyword

nonn,base,hard,more

Author

Corinna Regina Böger, Feb 14 2016

Status

approved