A216237 Happy palindromic numbers.

1, 7, 44, 262, 313, 383, 404, 464, 565, 656, 818, 888, 989, 1221, 1771, 1881, 2112, 3553, 4004, 4554, 4774, 5335, 5445, 5555, 7117, 7447, 7887, 8118, 8778, 11311, 11811, 12021, 12321, 12921, 14641, 15451, 15951, 17071, 17371, 18081, 18381, 20602, 21012

Offset

1,2

Comments

That is, happy numbers (A007770) that are palindromic (A002113).

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Formula

A103369(a(n)) * A136522(a(n)) = 1. - Reinhard Zumkeller, Mar 15 2013

Mathematica

palQ[n_] := Block[{d=IntegerDigits@n}, d == Reverse@d]; happyQ[n_] := Block[{w = n}, While[w > 6, w = Total[IntegerDigits[w]^2]]; w == 1]; Select[Range[21012], palQ[#] && happyQ[#] &] (* Giovanni Resta, Mar 14 2013 *)

Prog

(Haskell)
a216237 n = a216237_list !! (n-1)
a216237_list = filter ((== 1) . a136522) a007770_list
-- Reinhard Zumkeller, Mar 15 2013

Crossrefs

Cf. A002113, A007770.

Sequence in context: A203210 A323923 A026116 * A291388 A037531 A178719

Adjacent sequences: A216234 A216235 A216236 * A216238 A216239 A216240

Keyword

nonn,base,easy

Author

Jayanta Basu, Mar 14 2013

Status

approved