A hexagonal spiral Fibonacci sequence.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =3a(5) =5a(6) =8a(7) =14a(8) =23a(9) =38a(10) =63a(11) =102a(12) =168a(13) =272a(14) =445a(15) =720a(16) =1173a(17) =1898a(18) =3084a(19) =5004a(20) =8102a(21) =13143a(22) =21268a(23) =34472a(24) =55841a(25) =90376a(26) =146382a(27) =237028a(28) =383578a(29) =621046