来自在线整数百科全书的问候语!http://oeis.org/ Search: id:a324972 Showing 1-1 of 1 %I A324972 %S A324972 6,10,15,21,22,30,33,34,35,39,42,46,51,55,57,58,65,66,69,70,78,82,85, %T A324972 87,91,93,94,95,102,105,106,111,114,115,118,123,129,130,133,138,141, %U A324972 142,145,154,155,159,165,166,174,177,178,183,185,186,190,195,201,202 %N A324972 Squarefree polygonal numbers P(s,n) with s >= 3 and n >= 3. %C A324972 The main entry for this sequence is A090466 = polygonal numbers of order (or rank) greater than 2. %C A324972 The special polygonal numbers A324973 form a subsequence that contains all Carmichael numbers A002997. 见凯尔纳和索道2019。%3H A324972 Bernd C. Kellner和Jonathan Sondow,关于CalMekes和多边形数、伯努利多项式和Base-P数字的和,ARXIV:1902.10672 [数学,NT ],2019。%%H A324972维基百科,多边形数%F A324972 Squarefree P(s,n) = (n^2*(s-2)-n*(s-4))/2 with s >= 3 and n >= 3. %e A324972 P(3,3) = 6 which is squarefree, so a(1) = 6. %t A324972 mx = 250; n = s = 3; lst = {}; %t A324972 While[s < Floor[mx/3] + 2, a = (n^2 (s - 2) - n (s - 4))/2; %t A324972 If[a < mx + 1, AppendTo[lst, a], (s++; n = 2)]; n++]; lst = Union@lst; %t A324972 Select[lst, SquareFreeQ] %o A324972 (PARI) isok(n) = if (!3月24日A416917和A090466交会的A324972,包括AA24997,A324972,AN 249972,NN,%A324972,A324972,1,1%,A324972,BELND C.KELNELNY和Y-JONATON SONDOWAY,3月21日2019π的内容在OEIS最终用户许可协议下可用:HTTP:/OEIS.Org/许可证ISS(n),返回(0);(s=3,n=3+1,等多边形(n,s)