A106473 - OEIS

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A106473

Rows of A003989 expressed as base 10 numbers.

1, 11, 121, 1111, 12321, 111111, 1214121, 11311311, 121252121, 1111111111, 12341614321, 111111111111, 1212127212121, 11315311351311, 121412181214121, 1111111111111111, 12321612921612321, 111111111111111111

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OFFSET

0,2

COMMENTS

The all-1 entries occur at positions indexed by the n-th primes-2 (A040976). The 1's then sum to give n-th prime-1 (A006093). The sum of the digits of a(n) is given by A006579(n+1).

LINKS

Table of n, a(n) for n=0..17.

FORMULA

a(n) = sum{k=0..n, GCD(n-k+1, k+1)*10^k}.

CROSSREFS

Sequence in context: A080445 A033867 A307861 * A125315 A223676 A132583

Adjacent sequences: A106470 A106471 A106472 * A106474 A106475 A106476

KEYWORD

easy,nonn,base

AUTHOR

Paul Barry, May 03 2005

STATUS

approved