A061098 Concatenation of all numbers less than or equal to n other than the phi(n) numbers relatively prime to n.

1, 2, 3, 24, 5, 2346, 7, 2468, 369, 2456810, 11, 2346891012, 13, 24678101214, 3569101215, 246810121416, 17, 234689101214151618, 19, 2456810121415161820, 36791214151821, 24681011121416182022, 23, 23468910121415161820212224, 510152025, 246810121314161820222426

Offset

1,2

Comments

a(1) = 1 as the number itself is to be included. a(p) = p if p is a prime (by definition).

Links

Andrew Howroyd, Table of n, a(n) for n = 1..100

Example

a(6) = 2346, as 2,3,4,6 are not coprime to 6 and 1 and 5 are coprime to 6.

Prog

(PARI) a(n)={if(n==1, 1, fromdigits(concat([digits(k) | k<-[1..n], gcd(k, n)>1])))} \\ Andrew Howroyd, Nov 09 2019

Crossrefs

Cf. A000010.

Sequence in context: A001783 A095996 A308943 * A160630 A119619 A170909

Adjacent sequences: A061095 A061096 A061097 * A061099 A061100 A061101

Keyword

nonn,base

Author

Amarnath Murthy, Apr 19 2001

Extensions

Offset corrected and terms a(14) and beyond from Andrew Howroyd, Nov 09 2019

Status

approved