A388010 Irregular table T(n, k), n > 0, k = 1..A246600(n), read by rows; the n-th row lists the divisors d of n such that the binary representation of d can be obtained from the binary representation of n by changing any number of 1's to 0's.

1, 2, 1, 3, 4, 1, 5, 2, 6, 1, 7, 8, 1, 9, 2, 10, 1, 11, 4, 12, 1, 13, 2, 14, 1, 3, 5, 15, 16, 1, 17, 2, 18, 1, 19, 4, 20, 1, 21, 2, 22, 1, 23, 8, 24, 1, 25, 2, 26, 1, 3, 9, 27, 4, 28, 1, 29, 2, 6, 10, 30, 1, 31, 32, 1, 33, 2, 34, 1, 35, 4, 36, 1, 37, 2, 38, 1, 3, 39

Offset

1,2

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10954 (rows for n = 1..2^12 flattened)

Index entries for sequences related to binary expansion of n

Index entries for sequences related to divisors

Formula

T(n, 1) = A006519(n).

T(n, A246600(n)) = n.

Sum_{k = 1..A246600(n)} T(n, k) = A246601(n).

Example

Table T(n, k) begins:
  n   n-th row
  --  -----------
   1  1
   2  2
   3  1, 3
   4  4
   5  1, 5
   6  2, 6
   7  1, 7
   8  8
   9  1, 9
  10  2, 10
  11  1, 11
  12  4, 12
  13  1, 13
  14  2, 14
  15  1, 3, 5, 15

Prog

(PARI) row(n) = select(d -> bitand(n, d)==d, divisors(n))

Crossrefs

Cf. A006519, A246600 (row lengths), A246601 (row sums).

Sequence in context: A063804 A387934 A213800 * A224823 A372387 A395917

Adjacent sequences: A388007 A388008 A388009 * A388011 A388012 A388013

Keyword

nonn,base,tabf

Author

Rémy Sigrist, Sep 13 2025

Status

approved