|
|
A027721
|
|
Palindromes of form k^2 + k + 6.
|
|
4
|
|
|
6, 8, 606, 656, 818, 83238, 6177716, 6505056, 8343438, 8681868, 834545438, 21543634512, 69872727896, 83456565438, 85425552458, 8032131312308, 8255470745528, 8345676765438, 8716172716178, 8766434346678, 8915858585198, 8973808083798, 213296020692312
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
Palindromes h such that 4*h - 23 is a square. - Bruno Berselli, Aug 29 2018
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
palQ[n_] := Block[{d = IntegerDigits[n]}, d == Reverse[d]]; f[n_] := n^2 + n + 6; Select[f@ Range[0, 10^5], palQ] (* Giovanni Resta, Aug 29 2018 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|