A180436 Palindromic numbers which are sum of consecutive squares.

1, 4, 5, 9, 55, 77, 121, 181, 313, 434, 484, 505, 545, 595, 636, 676, 818, 1001, 1111, 1441, 1771, 4334, 6446, 10201, 12321, 14641, 17371, 17871, 19691, 21712, 40804, 41214, 42924, 44444, 44944, 46564, 51015, 65756, 69696, 81818, 94249, 97679, 99199

Offset: 1

Author

Zhining Yang, Jan 19 2011

Keywords

• nonn
• easy
• base

Comments

In more than one way: 554455, 9343439, ... (A267600) - Robert G. Wilson v, May 28 2012

Examples

			1001 is in the sequence because 1001 is palindromic and it can be written as sum of consecutive squares (1001 = 4^2 + 5^2 + 6^2 + ... + 13^2 + 14^2).
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10400 (terms < 10^18, first 228 terms from Robert G. Wilson v)

Crossrefs

Cf. A002113, A002779, A034705, A216446, A267600.

Programs

Mathematica

palQ[n_Integer] := Block[{idn = IntegerDigits[n]}, idn == Reverse[idn]]; lst = {}; k = 1; While[k < 1000, AppendTo[lst, Select[ Accumulate[ Range[k, 1000]^2], palQ]]; lst = Union@ Flatten@ lst; k++]; Select[lst, # < 10^6 &] (* Robert G. Wilson v, May 28 2012 *)