A281066 - OEIS

A281066

Concatenation R(n)R(n-1)R(n-2)...R(2)R(1) read mod n, where R(x) is the digit-reversal of x (with leading zeros not omitted).

0, 1, 0, 1, 1, 3, 3, 1, 0, 1, 4, 9, 5, 7, 6, 1, 6, 9, 17, 1, 15, 15, 19, 9, 21, 1, 18, 13, 28, 21, 26, 17, 15, 3, 16, 9, 30, 3, 15, 1, 1, 33, 10, 37, 36, 43, 22, 33, 19, 21, 48, 45, 2, 45, 26, 49, 27, 33, 33, 21, 48, 25, 36, 49, 36, 15, 22, 5, 27, 11, 42, 9, 2, 73, 21, 17, 59, 57, 5, 1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,6

LINKS

Indranil Ghosh, Table of n, a(n) for n = 1..20008

FORMULA

a(n) = A138793(n) (mod n).

EXAMPLE

a(13) = 31211101987654321 (mod 13) = 5.

MATHEMATICA

f[n_] := Mod[ FromDigits@ Fold[ Join[ Reverse@ IntegerDigits@#2, #1] &, {}, Range@ n], n]; Array[f, 80]

PROG

(Python)

def A281066(n):

s=""

for i in range(n, 0, -1):

s+=str(i)[::-1]

return int(s)%n # Indranil Ghosh, Jan 28 2017

(PARI) a(n) = my(s = ""); forstep (k=n, 1, -1, sk = digits(k); forstep (j=#sk, 1, -1, s = concat(s, sk[j]))); eval(s) % n; \\ Michel Marcus, Jan 28 2017

CROSSREFS

Cf. A004086, A061963, A095221, A114795, A138793.

Sequence in context: A130632 A229158 A290454 * A343875 A343874 A114795

Adjacent sequences: A281063 A281064 A281065 * A281067 A281068 A281069

KEYWORD

nonn,easy,look,base

AUTHOR

Robert G. Wilson v, Jan 14 2017

STATUS

approved