A301478 a(n) is the product of the n-th term of A301382 and its initial digit.

1, 4, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 25, 36, 40, 42, 44, 46, 48, 49, 50, 52, 54, 56, 58, 64, 81, 90, 93, 96, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131

Offset

1,2

Comments

The sequence is monotonically increasing, as stated in the Definition section of A301382.

Equivalently, these are the numbers of the form k * A000030(k) for some k > 0. - Rémy Sigrist, Mar 22 2018

Links

Jean-Marc Falcoz, Table of n, a(n) for n = 1..10000

Example

P is the product a(n) * [the first digit of a(n)] for every term of A301382:
a(1) = 1 is the product P = 1 * 1,
a(2) = 4 is the product P = 2 * 2,
a(3) = 9 is the product P = 3 * 3,
a(4) = 10 is the product P = 10 * 1,
a(5) = 11 is the product P = 11 * 1,
a(6) = 12 is the product P = 12 * 1,
Etc.

Prog

(PARI) p = vector(131, k, oo); for (n=1, #p, x = n*digits(n)[1]; if (x<=#p, p[x] = min(p[x], n))); for (k=1, #p, if (p[k] != oo, print1 (p[k]*digits(p[k])[1] ", "))) \\ Rémy Sigrist, Mar 22 2018

Crossrefs

Cf. A000030, A301382.

Sequence in context: A171001 A088037 A071768 * A173297 A161913 A020673

Adjacent sequences: A301475 A301476 A301477 * A301479 A301480 A301481

Keyword

nonn,base

Author

Eric Angelini and Jean-Marc Falcoz, Mar 22 2018

Status

approved