

A075345


Group the natural numbers such that the nth group contains n terms and the group sum is the smallest possible prime: (2), (1, 4), (3, 5, 9), (6, 7, 8, 10), (11, 12, 13, 14, 17), (15, 16, 18, 19, 20, 21), ... Sequence gives group sums.


4



2, 5, 17, 31, 67, 109, 179, 257, 373, 503, 673, 877, 1093, 1381, 1693, 2063, 2459, 2927, 3449, 4001, 4637, 5347, 6089, 6947, 7817, 8783, 9857, 10987, 12211, 13513, 14923, 16411, 17971, 19661, 21467, 23333, 25343, 27457, 29683, 32027, 34469, 37087
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OFFSET

1,1


COMMENTS

See A075348 for the groups. In case of several possibilities to write the given prime, e.g. a(3) = 3+5+9 = 3+6+8, the lexicographically smallest is to be chosen, here (3,5,9) rather than (3,6,8).  M. F. Hasler, Sep 26 2015


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000


PROG

(Haskell)
a075345 = sum . a075348_row  Reinhard Zumkeller, Sep 26 2015


CROSSREFS

Cf. A075346, A075347.
Cf. A075348.
Sequence in context: A172122 A101009 A066649 * A045705 A125822 A025537
Adjacent sequences: A075342 A075343 A075344 * A075346 A075347 A075348


KEYWORD

nonn,easy


AUTHOR

Amarnath Murthy, Sep 19 2002


EXTENSIONS

More terms from David Wasserman, Jan 16 2005


STATUS

approved



