This problem is certainly not for the meek...

Cliff

### Centered Hexamorphic Numbers by Cliff Pickover

Let us define centered hexagonal numbers as having the form: H =
3n(n-1)+1. They describe the number of grid points in nested concentric
hexagonal lattices. A centered hexagonal number is called "centered
hexamorphic" if it terminates with its associated centered hexagonal
integer. For example, n = 7 is centered hexamorphic because H (7)
equals 127. A convenient notation a_5 = aaaaa can be employed where the
subscript indicates the number of times the digit or group appears
consecutively. We note the following interesting infinite sequence:
H(5 0_k 1) = 7 5 0_(k-1) 1 5 0_k 1, k = 0,1,2, .... For example, k = 2
produces H(5001) = 75015001. Can the reader find any other infinite
sequences?

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Solution