A069559 Triangular numbers in which the k-th significant digit either divides k or is a multiple of k.

1, 3, 6, 15, 21, 28, 45, 66, 325, 666, 946, 1128, 1326, 2145, 2346, 2628, 2926, 4186, 8128, 8385, 8646, 8911, 11325, 11628, 14365, 18145, 18915, 51681, 52326, 54615, 54946, 58311, 111628, 118341, 152628, 214185, 258121, 614386, 1152921, 1211346

Offset

1,2

Comments

If the smallest prime divisor of n is > 7 then the n-th digit is 1.

Links

Table of n, a(n) for n=1..40.

Example

8646 is a member in which the fourth digit is 8 a multiple of 4, the third one is 6 a multiple of 3, the second one is 4 a multiple of 2 and the least significant digit is 6.

Crossrefs

Intersection of A000217 and A069570.

Cf. A069556, A069557, A069558.

Sequence in context: A256906 A095869 A292610 * A117748 A061066 A093799

Adjacent sequences: A069556 A069557 A069558 * A069560 A069561 A069562

Keyword

base,nonn

Author

Amarnath Murthy, Mar 22 2002

Extensions

More terms from Sascha Kurz, Mar 23 2002

Offset changed by Andrew Howroyd, Sep 19 2024

Status

approved