276 is the first triangular number that can be arrived at in three ways by adding pairs of triangular numbers together. This sequence, dubbed[4] 'Triple Triangle-Pair Numbers' is the sequence of integers: 276, 406, 666, ...
276 is the size of the largest set ofequiangular lines in 23 dimensions. The maximal set of such lines, derived from theLeech lattice, provides the highest dimension in which the "Gerzon bound" of is known to be attained; its symmetry group is thethird Conway group, Co3.[5][6]
276 is the smallest number for which it is not known if the correspondingaliquot sequence either terminates or ends in a repeating cycle.[7][8] 306 follows the same sequence as 276, since its aliquot sum is the same as 276.
276 is one of the five three-digittriangular numbers (along with 120,153, 300 and 666) that are present in the New Testament (specifically, in the books of John and Acts and Revelation; 276 being mentioned inActs 27). Menasgotz[4] argues that it is significant that two of those five (276 along with 666) constitute the first and the third of the Triple Triangle-Pair Numbers.
