

A180405


Smallest integer not yet present in the sequence such that the sum of the first a(n) terms of the sequence is a prime.


1



2, 1, 4, 6, 3, 7, 8, 10, 11, 15, 12, 18, 14, 16, 22, 24, 19, 31, 28, 20, 23, 37, 36, 30, 26, 34, 29, 35, 42, 38, 40, 32, 39, 45, 52, 44, 54, 46, 56, 60, 43, 51, 50, 64, 84, 48, 49, 53, 68, 58, 62, 78, 70, 66, 57, 59, 82, 92, 90, 88, 63, 77, 72, 94, 67, 79, 76, 102, 71, 81, 96, 100
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OFFSET

1,1


COMMENTS

From an idea of Eric Angelini with additional terms from D. S. McNeil.
The partial sums of the sequence are 2, 3, 7, 13, 16, 23, 31, 41, 52, ...
The sequence is selfdescriptive and says that the 2nd, 1st, 4th, 6th, 3rd, 7th, etc, term in the partial sums, namely 3, 2, 13, 23, 7, 31 etc, are primes.


LINKS

Table of n, a(n) for n=1..72.
Eric Angelini, The sum of the a(n) first digits of S is a prime
E. Angelini, The sum of the a(n) first digits of S is a prime [Cached copy, with permission]


CROSSREFS

Sequence in context: A306015 A171087 A105364 * A171007 A209168 A209162
Adjacent sequences: A180402 A180403 A180404 * A180406 A180407 A180408


KEYWORD

easy,nonn


AUTHOR

Paolo P. Lava, Sep 02 2010


EXTENSIONS

Examples replaced with a comment by R. J. Mathar, Nov 18 2010


STATUS

approved



