login
A275451
Number of occurrences of the string n in primorial(n).
1
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
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
KEYWORD
base,easy,nonn
AUTHOR
Ivan N. Ianakiev, Jul 28 2016
STATUS
approved