A256824 Reverse concatenation of distinct digits of all divisors of n in base 10.

1, 21, 31, 421, 51, 6321, 71, 8421, 931, 5210, 1, 64321, 31, 7421, 531, 86421, 71, 986321, 91, 54210, 7321, 21, 321, 864321, 521, 6321, 97321, 87421, 921, 653210, 31, 864321, 31, 74321, 7531, 9864321, 731, 98321, 931, 854210, 41, 764321, 431, 421, 95431, 64321

Offset: 1

Author

Jaroslav Krizek, Apr 10 2015

Keywords

• nonn
• base

Comments

Concatenation of elements of set of all digits of all divisors of n in decreasing order in base 10.

There are precisely 512 distinct terms of this sequence - see A256825 (possible values of a(n) in increasing order).

Minimal term is 1, maximal term is 9876543210.

Numbers n such that a(n) = 1 are in A243534, numbers n such that a(n) = 9876543210 are in A095050.

See A256826 - the smallest numbers k such that a(k) = A256825(n).

Examples

			For n = 12; list of divisors of 12 in base 10: 1, 2, 3, 4, 6, 12 contains five distinct digits (1, 2, 3, 4, 6) whose reverse concatenation is 64321.
		

Links

• Jaroslav Krizek, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A009995, A095050, A243534, A256825, A256826.

Programs

Magma

[Seqint(Setseq(Set(Sort(&cat[Intseq(d): d in Divisors(n)])))): n in [1..100]];

Mathematica

Table[FromDigits[Reverse[Union[Flatten[IntegerDigits[Divisors[n]]]]]],{n,100}] (* Ivan N. Ianakiev, Apr 14 2015 *)

PARI

a(n) = {my(v = []); fordiv(n, d, v = vecsort(concat(v, digits(d)),,8)); subst(Polrev(v), x, 10);} \\ Michel Marcus, Apr 11 2015