OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..200
FORMULA
EXAMPLE
a(3) = 78910 mod 456 = 22.
From Jon E. Schoenfield, Feb 23 2021: (Start)
.
concatenation of concatenation of
n T(n-1)+1..T(n) T(n)+1..T(n+1) a(n)
-- ---------------- ---------------- -----
1 1 23 0
2 23 456 19
3 456 78910 22
4 78910 1112131415 52785
(End)
MATHEMATICA
ccat[a_, b_]:=FromDigits[Flatten[IntegerDigits/@Range[a, b]]]; modc[n_]: = Module[{w=(n(n-1))/2+1, x=(n(n+1))/2, y, z}, y=x+1; z=2x-w+2; Mod[ccat[y, z], ccat[w, x]]]; Array[modc, 20] (* Harvey P. Dale, Nov 27 2012 *)
CROSSREFS
KEYWORD
base,nonn,less
AUTHOR
Amarnath Murthy, Jun 10 2004
EXTENSIONS
More terms from Hagen von Eitzen, Jun 17 2009
a(14) from Harvey P. Dale, Nov 27 2012
STATUS
approved