cp's OEIS Frontend

A319746 Quasi-Repfigit numbers (or Quasi-Keith numbers).

%I A319746 #11 Jun 02 2025 15:22:12
%S A319746 12,18,32,35,43,59,142,187,241,265,610,778,1521,2163,2625,3267,3729,
%T A319746 9242,15905,16725,18852,56207,63265,87538,94596,333718,780890,839383,
%U A319746 959394,1114534,1745662,2198585,2424613,2815415,5501438,7371962,9717796,21010738,27800086,31173396
%N A319746 Quasi-Repfigit numbers (or Quasi-Keith numbers).
%C A319746 Numbers n>9 with following property: form a sequence b(i) whose initial terms are the t digits of n, later terms given by rule that b(i) = sum of t previous terms; then n - 1 or n + 1 appears in the sequence.
%e A319746 a(1) = 12 because 1 + 2 = 3, 2 + 3 = 5, 3 + 5 = 8, 5 + 8 = 13 = 12 + 1.
%e A319746 a(2) = 18 because 1 + 8 = 9, 8 + 9 = 17 = 18 - 1.
%p A319746 P:=proc(q) local b, k,n,v; for n from 1 to q do b:=ilog10(n)+1;
%p A319746 if b>1 then v:=[]; for k from 1 to b do
%p A319746 v:=[op(v),trunc(n/10^(b-k)) mod 10]; od; v:=[op(v),add(v[k],k=1..b)];
%p A319746 while v[nops(v)]<n-1 do v:=[op(v),add(v[k], k=nops(v)-b+1..nops(v))]; od;
%p A319746 if v[nops(v)]=n-1 or v[nops(v)]=n+1 then print(n); fi; fi; od; end: P(10^7);
%Y A319746 Cf. A007629, A130010.
%K A319746 nonn,base
%O A319746 1,1
%A A319746 _Paolo P. Lava_, Sep 27 2018