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

%I A382210 #7 Mar 18 2025 21:41:15
%S A382210 2,3,5,5,7,11,17,11,13,17,23,31,41,53,67,83,101,17,19,23,29,37,47,59,
%T A382210 73,89,107,127,149,173,199,227,257,41,43,47,53,61,71,83,97,113,131,
%U A382210 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
%N A382210 Irregular triangle read by rows: T(n,k) = k^2 - k + (A003173(n) + 1)/4 with 1 <= k < (A003173(n) + 1)/4.
%D A382210 John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See p. 225.
%e A382210 The irregular triangle begins as:
%e A382210    2;
%e A382210    3,  5;
%e A382210    5,  7, 11, 17;
%e A382210   11, 13, 17, 23, 31, 41, 53, 67, 83, 101;
%e A382210   17, 19, 23, 29, 37, 47, 59, 73, 89, 107, 127, 149, 173, 199, 227, 257;
%e A382210   ...
%t A382210 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
%Y A382210 Cf. A003173, A048058, A302445.
%K A382210 nonn,easy,fini,full,tabf
%O A382210 4,1
%A A382210 _Stefano Spezia_, Mar 18 2025