This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A244752 Square array read by antidiagonals in which rows are indexed by composite numbers w and row w gives n such that n^(w-1) == 1 (mod w^2). 7
 17, 33, 37, 49, 73, 65, 65, 109, 129, 80, 81, 145, 193, 82, 101, 97, 181, 257, 161, 201, 145, 113, 217, 321, 163, 301, 289, 197, 129, 253, 385, 242, 401, 433, 393, 26, 145, 289, 449, 244, 501, 577, 589, 199, 257, 161, 325, 513, 323, 601, 721, 785, 224, 513 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS Table starts w=4: 17, 33, 49, 65, 81, 97, 113, .... w=6: 37, 73, 109, 145, 181, 217, .... w=8: 65, 129, 193, 257, 321, 385, .... w=9: 80, 82, 161, 163, 242, 244, .... w=10: 101, 201, 301, 401, 501, 601, .... w=12: 145, 289, 433, 577, 721, 865, .... w=14: 197, 393, 589, 785, 981, .... .... We can say that "w is a Wieferich pseudoprime to base n". Any prime factor of w is a Wieferich prime to base n. LINKS Robert Price, Table of n, a(n) for n = 2..1276 MATHEMATICA T = {}; For[w = 4, w <= 100, w++,   If[PrimeQ[w], Continue[]];   t = {};   For [n = 2, n <= 10^5, n++,    If[Mod[n^(w - 1), w^2] == 1, AppendTo[t, n]]];   AppendTo[T, t]]; Print[TableForm[T]]; A244752 = {}; For[c = 1, c <= 50, c++,   For[r = 1, r <= c, r++, AppendTo[A244752, T[[r]][[c - r + 1]]]]]; A244752 (* Robert Price, Sep 07 2019 *) PROG (PARI) forcomposite(w=2, 20, print1("w=", w, ": "); for(n=2, 10^3, if(Mod(n, w^2)^(w-1)==1, print1(n, ", "))); print("")) CROSSREFS Cf. A001220, A240719, A244249. Sequence in context: A162504 A085255 A283395 * A138393 A044062 A044443 Adjacent sequences:  A244749 A244750 A244751 * A244753 A244754 A244755 KEYWORD nonn,tabl AUTHOR Felix FrÃ¶hlich, Jul 05 2014 EXTENSIONS a(17)-a(55) from Robert Price, Sep 07 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 8 14:38 EST 2019. Contains 329865 sequences. (Running on oeis4.)