A050721 Primes arising in A083571.
2, 3, 11, 109, 173, 5513600773
Offset: 1
Links
- P. De Geest, Subsets of palindromic triangulars
This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
[k:k in [1..5000000]| Intseq(Binomial(k+1,2)) eq Reverse(Intseq(Binomial(k+1,2)))]; // Marius A. Burtea, Jul 16 2019
palQ[n_]:= Reverse[x=IntegerDigits[n]]==x; t={}; Do[If[palQ[n*(n+1)/2],AppendTo[t,n]],{n,4*10^6}]; t (* Jayanta Basu, May 13 2013 *)
Position[Accumulate[Range[371*10^4]],?PalindromeQ]//Flatten (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale, Jun 12 2020 *)
ispal(n)=n=digits(n); for(i=1, #n\2, if(n[i]!=n[#n+1-i], return(0))); 1 is(n)=ispal(n*(n+1)/2) \\ Charles R Greathouse IV, May 15 2013
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