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URL: https://oeis.org/A357772

⇱ A357772 - OEIS

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A357772
Numbers with a sum of digits which is not 7-smooth.
1
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
1,1
FORMULA
a(n) ~ n.
EXAMPLE
2 + 9 = 11 which is not of the form 2^a*3^b*5^c*7^d, so 29 is in the sequence.
PROG
(PARI) smooth(n, s)=forprime(p=2, s, n/=p^valuation(n, p)); n==1
is(n)=!smooth(sumdigits(n), 7)
CROSSREFS
Cf. A087144.
Sequence in context: A069530 A259032 A087144 * A114616 A166311 A159887
KEYWORD
nonn,easy,base
AUTHOR
STATUS
approved