A275451 Number of occurrences of the string n in primorial(n).

0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 2, 2, 1, 1, 0, 2, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 3, 0, 0, 3, 2, 2, 1, 1, 1, 1, 2, 0, 5, 4, 4, 2, 4, 4, 0, 0, 4, 2, 4, 3, 1, 0, 1, 0, 1, 2

Offset

1,36

Links

Table of n, a(n) for n=1..82.

Formula

a(A275450(n)) > 0.

Example

Primorial(3) equals 30, which contains 3 once, therefore a(3) = 1.

Mathematica

primorial[n_]:=Product[Prime[i], {i, 1, n}];
Table[Length[StringPosition[ToString[primorial[n]], ToString[n]]], {n, 1, 100}]
SequenceCount[IntegerDigits[#[[1]]], IntegerDigits[#[[2]]]]&/@With[ {nn=90}, Thread[ {FoldList[ Times, Prime[Range[nn]]], Range[nn]}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Sep 16 2017 *)

Crossrefs

Cf. A002110 (primorial numbers), A275450.

Sequence in context: A133685 A281492 A112183 * A269317 A119557 A125919

Adjacent sequences: A275448 A275449 A275450 * A275452 A275453 A275454

Keyword

base,easy,nonn

Author

Ivan N. Ianakiev, Jul 28 2016

Status

approved