A217411 -id:A217411 - cp's OEIS frontend

A217410 Numbers of the form 3^r*7^s whose decimal representations are such that each digit 0-9 appears a prime number of times.

127194058437252046971768387, 13246352657250963177488450589, 1461157813024707015061910842923, 12415617112031938486785960616347, 147856680363717377959300292543841

Offset: 1

James G. Merickel, Oct 02 2012

See the formula section for more data, and the others in cross-reference for similar sequences and motivation.

			A217411(1)=37 and A217412(1)=10, so this sequence's first term is (3^37)*(7^10).  It is the smallest number with exactly 3 and 7 as its prime factors to have decimal representation with each digit 0-9 counted a prime number of times. The digits 0, 2, 3, 5, 6 and 9 occur two times each; 1, 4 and 8 occur three times each; and 7 occurs five times.

Cf. A216854, A217411, A217412, A217404, A217407, A217410, A217416, A217419, A217422, A217425, A217428, A217431.

a(n) = 3^A217411(n) * 7^A217412(n).

A217412 7-adic valuation of A217410.

Original entry on oeis.org

10, 9, 34, 8, 20, 7, 8, 8, 15, 14, 1, 26, 39, 20, 6, 57, 949

Offset: 1

James G. Merickel, Oct 02 2012

These are the values s for numbers of the form (3^r)*(7^s) in the main sequence.

			A217410(1)=(3^37)*(7^10), so this sequence's first term is 10.

Cf. A217410, A217411.

cp's OEIS Frontend

A217410 Numbers of the form 3^r*7^s whose decimal representations are such that each digit 0-9 appears a prime number of times.

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