A077321 Rearrange primes so as to form a triangle in which n-th row contains the n smallest primes == 1 (mod n) which have not occurred earlier.
2, 3, 5, 7, 13, 19, 17, 29, 37, 41, 11, 31, 61, 71, 101, 43, 67, 73, 79, 97, 103, 113, 127, 197, 211, 239, 281, 337, 89, 137, 193, 233, 241, 257, 313, 353, 109, 163, 181, 199, 271, 307, 379, 397, 433, 131, 151, 191, 251, 311, 331, 401, 421, 431, 461, 23, 419, 463, 617
Offset: 1
Examples
Triangle begins: 2 3 5 7 13 19 17 29 37 41 11 31 61 71 101 ...
Links
- Ivan Neretin, Table of n, a(n) for n = 1..5050
Programs
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Maple
A077321 := proc(nmax) local n,a,i,p; a := []; n :=1; while nops(a) < nmax do for i from 1 to n do p := 2; while ( p in a ) or (p-1) mod n <> 0 do p := nextprime(p); od; a := [op(a),p]; od; n := n+1; od; RETURN(a); end: A077321(100); # R. J. Mathar, Feb 03 2007
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Mathematica
A077321[nmax_] := Module[{n = 1, a = {}, i, p}, While[ Length[a] < nmax, For[i = 1, i <= n, i++, p = 2; While[ MemberQ[a, p] || Mod[p - 1, n] != 0, p = NextPrime[p]]; a = Append[a, p]]; n = n + 1]; Return[a]]; A077321[100] (* Jean-François Alcover, May 30 2023, after R. J. Mathar *)
Extensions
More terms from Ray Chandler, Dec 10 2004
Edited by N. J. A. Sloane, Sep 14 2008 at the suggestion of R. J. Mathar