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A256398 Palindromes of the form i^2 + reverse(i)^2. 2
0, 2, 8, 101, 242, 404, 585, 909, 10001, 12221, 14841, 20402, 24642, 40004, 44244, 48884, 50805, 90009, 96269, 1000001, 1030301, 1080801, 1210121, 1244421, 1298921, 1440441, 1478741, 1690961, 2004002, 2234322, 2468642, 2484842, 4000004, 4050504, 4410144 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Is 864666666468 the only term in this sequence that has an even number of digits? - Jon E. Schoenfield, Mar 30 2015

LINKS

Bui Quang Tuan, Table of n, a(n) for n = 1..458

EXAMPLE

Palindrome 585 is in the sequence because 585 = 12^2 + 21^2.

The smallest term that can be obtained in more than one way is 125484521 = 11020^2 + 2011^2 = 11200^2 + 211^2. Are there any terms that can be obtained in more than two ways? - Jon E. Schoenfield, Mar 30 2015

MATHEMATICA

Sort@ DeleteDuplicates@ Select[Table[n^2 + FromDigits[Reverse[IntegerDigits@ n]]^2, {n, 10000}], Reverse@ IntegerDigits@ # == IntegerDigits@ # &] (* Michael De Vlieger, Mar 28 2015 *)

PROG

(PARI) rev(n)=r=""; d=digits(n); for(i=1, #d, r=concat(Str(d[i]), r)); eval(r)

v=[]; for(n=0, 10^4, if(rev(P=(n^2+rev(n)^2))==P, v=concat(v, P))); vecsort(v, , 8) \\ Derek Orr, Mar 29 2015

CROSSREFS

Cf. A002113 (palindromes), A056964 (n+rev(n)).

Cf. A256437.

Sequence in context: A119654 A333439 A173976 * A008926 A136468 A322643

Adjacent sequences:  A256395 A256396 A256397 * A256399 A256400 A256401

KEYWORD

nonn,base

AUTHOR

Bui Quang Tuan, Mar 28 2015

EXTENSIONS

Data corrected by Derek Orr, Mar 29 2015

STATUS

approved

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Last modified June 19 16:01 EDT 2021. Contains 345144 sequences. (Running on oeis4.)