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A061098 Concatenation of all numbers less than or equal to n other than the phi(n) numbers relatively prime to n. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 17 16:03 EDT 2021. Contains 343980 sequences. (Running on oeis4.)