A280987 {Concatenation n, n-1, n-2, ...3,2,1} mod sigma(n).

0, 0, 1, 2, 3, 9, 1, 6, 4, 1, 9, 21, 1, 9, 9, 16, 9, 24, 1, 33, 17, 1, 9, 21, 0, 9, 1, 41, 21, 33, 17, 6, 33, 19, 33, 25, 25, 21, 1, 1, 33, 81, 17, 21, 45, 1, 33, 85, 49, 69, 57, 77, 27, 81, 1, 81, 1, 1, 21, 57, 59, 81, 33, 60, 21, 33, 45, 51, 81, 1, 9, 66, 41, 9, 97, 1, 81, 81, 1, 57, 117, 73, 33, 145

Offset

1,4

Links

Indranil Ghosh, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000422(n) mod A000203(n).

Example

For n = 11, A000422(n) mod sigma(n) = 1110987654321 mod 12 = 9. S0 a(11) = 9.

Mathematica

Table[Mod[FromDigits[Flatten[IntegerDigits/@Range[n, 1, -1]]], DivisorSigma[ 1, n]], {n, 90}] (* Harvey P. Dale, Jul 01 2020 *)

Prog

(Python)
def sigma(n):
    s=0
    for i in range(1, n+1):
        if n%i==0:
            s+=i
    return s
def C(n):
    s=""
    for i in range(n, 0, -1):
        s+=str(i)
    return int(s)
for i in range(1, 10001):
    print str(i)+" "+str(C(i)%sigma(i))

Crossrefs

Cf. A000203, A000422, A114795.

Sequence in context: A201407 A109197 A021811 * A030367 A028508 A021422

Adjacent sequences: A280984 A280985 A280986 * A280988 A280989 A280990

Keyword

nonn,base

Author

Indranil Ghosh, Jan 12 2017

Status

approved