A180405 - OEIS

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.

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 self-descriptive 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

Neal Gersh Tolunsky, Table of n, a(n) for n = 1..10000

Eric Angelini, The sum of the a(n) first digits of S is a prime

Eric Angelini, The sum of the a(n) first digits of S is a prime [Cached copy, with permission]

CROSSREFS

Cf. A054408, A171007 (digits version), A363379 (complement).

Sequence in context: A306015 A171087 A105364 * A171007 A209168 A209162

Adjacent sequences: A180402 A180403 A180404 * A180406 A180407 A180408

KEYWORD

easy,nonn,changed

AUTHOR

Paolo P. Lava, Sep 02 2010

EXTENSIONS

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

STATUS

approved