A382210 Irregular triangle read by rows: T(n,k) = k^2 - k + (A003173(n) + 1)/4 with 1 <= k < (A003173(n) + 1)/4.

2, 3, 5, 5, 7, 11, 17, 11, 13, 17, 23, 31, 41, 53, 67, 83, 101, 17, 19, 23, 29, 37, 47, 59, 73, 89, 107, 127, 149, 173, 199, 227, 257, 41, 43, 47, 53, 61, 71, 83, 97, 113, 131, 151, 173, 197, 223, 251, 281, 313, 347, 383, 421, 461, 503, 547, 593, 641, 691, 743, 797, 853, 911, 971, 1033, 1097, 1163, 1231, 1301, 1373, 1447, 1523, 1601

Offset: 4

Author

Stefano Spezia, Mar 18 2025

Keywords

• nonn
• easy
• fini
• full
• tabf

Examples

			The irregular triangle begins as:
   2;
   3,  5;
   5,  7, 11, 17;
  11, 13, 17, 23, 31, 41, 53, 67, 83, 101;
  17, 19, 23, 29, 37, 47, 59, 73, 89, 107, 127, 149, 173, 199, 227, 257;
  ...
		

References

• John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See p. 225.

Crossrefs

Cf. A003173, A048058, A302445.

Programs

Mathematica

Heegner:={1, 2, 3, 7, 11, 19, 43, 67, 163};A003173[n_]:=Part[Heegner,n]; T[n_,k_]:=k^2-k+(A003173[n]+1)/4;Table[T[n,k],{n,4,9},{k,(A003173[n]+1)/4-1}]//Flatten