OFFSET
1,3
COMMENTS
This sequence is infinite since 2^k+1 is a term for all k>1 (Trigg, 1974).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..128
Charles W. Trigg, Infinite sequences of palindromic triangular numbers, The Fibonacci Quarterly, Vol. 12, No. 2 (1974), pp. 209-212.
Maciej Ulas, On certain diophantine equations related to triangular and tetrahedral numbers, arXiv:0811.2477 [math.NT], 2008.
EXAMPLE
MATHEMATICA
Select[Range[0, 10^5], PalindromeQ[IntegerDigits[#*(# + 1)/2, 2]] &]
PROG
(PARI) isok(k) = my(b=binary(k*(k+1)/2)); b == Vecrev(b); \\ Michel Marcus, Jan 28 2022
(Python)
def ok(n): b = bin(n*(n+1)//2)[2:]; return b == b[::-1]
print([k for k in range(80000) if ok(k)]) # Michael S. Branicky, Jan 28 2022
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amiram Eldar, Jan 28 2022
STATUS
approved