A026471 a(n) = least positive integer > a(n-1) and not of the form a(i) + a(j) + a(k) for 1 <= i < j < k <= n.
1, 2, 3, 4, 5, 13, 14, 15, 25, 26, 27, 37, 38, 48, 49, 50, 60, 61, 71, 72, 73, 83, 84, 94, 95, 96, 106, 107, 117, 118, 119, 129, 130, 140, 141, 142, 152, 153, 163, 164, 165, 175, 176, 186, 187, 188, 198, 199, 209, 210, 211, 221, 222, 232, 233, 234, 244, 245, 255
Offset: 1
Links
- Wieb Bosma, Rene Bruin, Robbert Fokkink, Jonathan Grube, Anniek Reuijl, and Thian Tromp, Using Walnut to solve problems from the OEIS, arXiv:2503.04122 [math.NT], 2025.
- Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).
Formula
{1, 5, 13} union {n congruent 2, 3, 4, 14, 15 mod 23}, proved by Matthew Akeran. - Ralf Stephan, Nov 15 2004
G.f.: (9*x^11-7*x^10+9*x^8+7*x^5+x^4+x^3+x^2+x+1)*x/(x^6-x^5-x+1). - Alois P. Heinz, Aug 06 2018
Extensions
Edited by Floor van Lamoen, Sep 02 2002