A380359 - OEIS

A380359

a(n) is the number of integers in base n such that all the integers given by their first k digits are divisible by k and which cannot be extended further.

1, 3, 8, 21, 54, 145, 367, 1039, 2492, 6709, 16799, 46610, 95597, 368134, 831886, 2245056, 6084180, 15798495, 41456343, 119786906, 292818176, 788255058, 2061079489, 5753392327, 14984432350

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OFFSET

2,2

LINKS

Table of n, a(n) for n=2..26.

Wikipedia, Polydivisible number.

EXAMPLE

a(10)=2492 because from all A271374(10)=20457 polydivisible numbers, only 2492 cannot be further expanded into a larger polydivisible number. One such number is 4836545640368400: 4 is divisible by 1, 48 is divisible by 2, 483 is divisible by 3, 4836 is divisible by 4, and so on until 4836545640368400 which is divisible by 16; but one cannot extend it further since no digit (0 to 9) appended to 4836545640368400 would result in a number divisible by k=17.

CROSSREFS

Cf. A271374, A109783, A109032.

Sequence in context: A335807 A005580 A292619 * A231222 A231436 A027932

Adjacent sequences: A380356 A380357 A380358 * A380360 A380361 A380362

KEYWORD

nonn,base,more

AUTHOR

Inigo Quilez, Jan 22 2025

STATUS

approved