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A216446 Palindromic numbers which can be written as the sum of two or more consecutive squares. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

V. Raman and Giovanni Resta, Table of n, a(n) for n = 1..10306 (terms < 10^18, first 298 terms from V. Raman)

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 *)

CROSSREFS

Cf. A034705, A180436, A267600 (terms with more than one representation).

Sequence in context: A247711 A284066 A244439 * A307991 A015221 A035305

Adjacent sequences:  A216443 A216444 A216445 * A216447 A216448 A216449

KEYWORD

nonn,base

AUTHOR

V. Raman, Sep 07 2012

EXTENSIONS

Errors in previous b-file noticed by Riley Waugh, Jun 13 2018

STATUS

approved

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Last modified April 8 02:27 EDT 2020. Contains 333312 sequences. (Running on oeis4.)