A196495 Smallest multidigit palindromic centered n-gonal number.

15151, 181, 141, 919, 22, 121, 55, 11, 111, 121, 131, 141, 151, 161, 171, 55, 191, 121, 22, 189949981, 484, 505, 151, 11311, 757, 16661, 88, 181, 72727, 33, 1111111, 10201, 10501, 757, 2636362, 17671, 51715, 121, 616, 36163, 44, 1856581, 676, 12256565221

Offset

3,1

Comments

Is it true that there is no term for n = 56? - T. D. Noe, Oct 03 2011

No, the smallest multidigit palindromic centered 56-gonal number is 14075098988989057041 with base 709000780. - Patrick De Geest, Apr 25 2021

Links

Table of n, a(n) for n=3..46.

Patrick De Geest, Palindromic Centered Polygonal Numbers

T. Trotter, Polygonal numbers

Example

15151 is the smallest palindromic centered triangular number.
121 is the smallest palindromic centered 40-gonal number.

Mathematica

palin[n_] := Module[{d = IntegerDigits[n]}, d == Reverse[d]]; Table[n = 1; While[num = n*k*(n-1)/2 + 1; num < 10 || ! palin[num], n++]; num, {k, 3, 50}] (* T. D. Noe, Oct 03 2011 *)

Crossrefs

Sequence in context: A004955 A004975 A157436 * A031623 A105924 A259395

Adjacent sequences: A196492 A196493 A196494 * A196496 A196497 A196498

Keyword

nonn,base

Author

Kausthub Gudipati, Oct 03 2011

Status

approved