A275999 Smallest nonnegative number k such that A240088(k) = n.

0, 3, 1, 5, 10, 19, 15, 22, 31, 51, 61, 37, 82, 71, 126, 96, 92, 136, 162, 187, 206, 276, 191, 261, 236, 247, 317, 302, 401, 292, 422, 547, 456, 544, 551, 612, 591, 577, 521, 666, 742, 726, 682, 877, 796, 1052, 961, 1046, 1171, 1027, 954, 1017, 1006, 1207, 1396, 1262, 1311, 1496, 1482, 1571, 1717

Offset: 1

Author

Robert G. Wilson v, Aug 17 2016

Keywords

• nonn

Examples

			a(1) = 0 since A240088(0) = 1, namely 0+0+0;
a(2) = 3 since A240088(3) = 2, namely 1+1+1 or 3+0+0;
a(3) = 1 since A240088(1) = 3, namely 1+0+0 or 0+1+0 or 0+0+1;
with triangular number followed by square number followed by pentagonal number.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1007 terms from Robert G. Wilson v)

Crossrefs

Cf. A240088.

Programs

Mathematica

f[n_] := Block[{c = pi = 0, pn, plmt = Floor[(Sqrt[1 + 24 n] + 7)/6], ti, tlmt}, While[pi < plmt, ti = 0; pn = pi (3pi -1)/2; tlmt = Floor[(Sqrt[1 +8(n - pn)] + 1)/2] +1; While[ti < tlmt, If[IntegerQ[Sqrt[n - pn - ti (ti + 1)/2]], c++]; ti++]; pi++]; c]; t = 0*Range@ 1000; k = 0; While[k < 100001, a = f@ k; If[ t[[a]] == 0, t[[a]] = k]; k++]; t