A248500 Numbers m that are not coprime to A059995(m): floor(m/10).

2, 3, 4, 5, 6, 7, 8, 9, 20, 22, 24, 26, 28, 30, 33, 36, 39, 40, 42, 44, 46, 48, 50, 55, 60, 62, 63, 64, 66, 68, 69, 70, 77, 80, 82, 84, 86, 88, 90, 93, 96, 99, 100, 102, 104, 105, 106, 108, 110, 120, 122, 123, 124, 126, 128, 129, 130, 140, 142, 144, 146, 147

Offset: 1

Author

Stanislav Sykora, Oct 07 2014

Keywords

• nonn
• base
• easy

Comments

Definition of 'being coprime' and special-case conventions are as in Wikipedia. In particular, when m<10 then floor(m/10)=0, and zero is coprime only to 1. The complementary sequence is A248499.

Examples

			2 is a member because gcd(2,0)=2 > 1.
100 is also a member because gcd(100,10)=10 > 1.
125 is not a member because 125 and 12 are coprime, i.e., gcd(125,12)=1.
		

Links

• Stanislav Sykora, Table of n, a(n) for n = 1..20000
• Wikipedia, Coprime integers

Crossrefs

Cf. A059995, A248499, A248501, A248502.

Programs

PARI

a=vector(20000);
i=n=0; while(i++, if(gcd(i, i\10)!=1, a[n++]=i; if(n==#a, break))); a

Formula

gcd(a(n),floor(a(n)/10)) > 1.