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A229236
Palindromic triangular number with palindromic index.
2
1, 3, 6, 66, 3003, 66066, 617716, 3544453, 6172882716, 30416261403, 61728399382716, 66056806460865066, 3549632679762369453, 354963215686512369453, 30416741529792514761403, 35496321045754012369453, 3041674104186814014761403
OFFSET
1,2
LINKS
Shyam Sunder Gupta, Table of n, a(n) for n = 1..18
EXAMPLE
a(5)=3003 because 3003 is 77th triangular number and 77 is palindrome.
MATHEMATICA
Select[Table[{n, (n(n+1))/2}, {n, 10^8}], AllTrue[#, PalindromeQ]&][[;; , 2]] (* Harvey P. Dale, Jun 04 2023 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Shyam Sunder Gupta, Sep 17 2013
EXTENSIONS
Previous Mathematica program replaced by Harvey P. Dale, Jun 04 2023
STATUS
approved