OFFSET
1,2
COMMENTS
LINKS
Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,0,0,0,0,1,-1).
FORMULA
From Chai Wah Wu, Mar 30 2023: (Start)
a(n) = a(n-1) + a(n-13) - a(n-14) for n > 14.
G.f.: x*(3*x^13 + 4*x^12 + 4*x^11 - 9*x^10 + 4*x^9 + 4*x^8 - 9*x^7 + 4*x^6 + 4*x^5 - 9*x^4 + 4*x^3 + 4*x^2 + 4*x + 1)/(x^14 - x^13 - x + 1). (End)
PROG
(PARI) {u=[a=1]; (chk(n)=(!#u||(n>u[1]&&!setsearch(u, n)))&&(u=setunion(u, [n]))&&!while(#u>1&&u[2]==u[1]+1, u=u[^1])); for(n=1, 99, print1(a", "); for(k=-sqrtint(a+!a-1), 9e9, k^2>1||next; chk(a+k*abs(k))||next; a+=k*abs(k); break))}
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Eric Angelini and M. F. Hasler, Oct 23 2016
STATUS
approved