a(n) is the smallest base b such that (b+1)^n in base b is a palindrome.

Terms

a(0) =2a(1) =2a(2) =2a(3) =7a(4) =11a(5) =21a(6) =36a(7) =71a(8) =127a(9) =253a(10) =463a(11) =925a(12) =1717a(13) =3433a(14) =6436a(15) =12871a(16) =24311a(17) =48621a(18) =92379a(19) =184757a(20) =352717a(21) =705433a(22) =1352079a(23) =2704157a(24) =5200301a(25) =10400601a(26) =20058301a(27) =40116601a(28) =77558761a(29) =155117521