A357772 Numbers with a sum of digits which is not 7-smooth.

29, 38, 47, 49, 56, 58, 65, 67, 74, 76, 83, 85, 89, 92, 94, 98, 119, 128, 137, 139, 146, 148, 155, 157, 164, 166, 173, 175, 179, 182, 184, 188, 191, 193, 197, 199, 209, 218, 227, 229, 236, 238, 245, 247, 254, 256, 263

Offset: 1

Author

Charles R Greathouse IV, Oct 13 2022

Keywords

• nonn
• easy
• base

Examples

			2 + 9 = 11 which is not of the form 2^a*3^b*5^c*7^d, so 29 is in the sequence.
		

Crossrefs

Cf. A087144.

Programs

PARI

smooth(n,s)=forprime(p=2,s,n/=p^valuation(n,p)); n==1
is(n)=!smooth(sumdigits(n),7)

Formula

a(n) ~ n.