

A216446


Palindromic numbers which can be written as the sum of two or more consecutive squares.


3



5, 55, 77, 181, 313, 434, 505, 545, 595, 636, 818, 1001, 1111, 1441, 1771, 4334, 6446, 17371, 17871, 19691, 21712, 41214, 42924, 44444, 46564, 51015, 65756, 81818, 97679, 99199, 108801, 127721, 137731, 138831, 139931, 148841, 161161, 166661, 171171, 188881
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OFFSET

1,1


LINKS



EXAMPLE

636 is in the sequence because it is a palindrome and 636 = 4^2+5^2+6^2+7^2+8^2+9^2+10^2+11^2+12^2.


MATHEMATICA

palQ[n_] := Block[{d = IntegerDigits@ n}, d == Reverse@ d]; upto = 10^6; Union[ Reap[ For[i=1, s=i^2 + (i+1)^2; s < upto, i++, For[j=i+1, s < upto, j++; s += j^2, If[palQ[s], Sow@ s]]]][[2, 1]]] (* Giovanni Resta, Jun 14 2018 *)
With[{nn=200}, Select[Union[Flatten[Table[Total/@Partition[Range[nn]^2, n, 1], {n, 2, nn}]]], PalindromeQ]] (* Harvey P. Dale, Oct 17 2021 *)


CROSSREFS



KEYWORD

nonn,base


AUTHOR



EXTENSIONS

Errors in previous bfile noticed by Riley Waugh, Jun 13 2018


STATUS

approved



