

A112665


Numbers that cannot be expressed as a sum of 2 triangular numbers and a power of 2.


1



6222, 18081, 22161, 23428, 27342, 29847, 36115, 44137, 47677, 50211, 52534, 56751, 57220, 64008, 70146, 78210, 79632, 81003, 82396, 83538, 84531, 85603, 92374, 92847, 96441, 96873, 97054, 97461, 103572, 103935, 109045, 119685, 121134
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OFFSET

1,1


COMMENTS

Sequence proposed by Livio Zucca on it.hobby.enigmi. First prime number appearing is 152539. (Cf. A112625)


LINKS

Table of n, a(n) for n=1..33.


EXAMPLE

6221 and 6223 are not in the sequence since they can be expressed as 6221 = T(105) + T(32) + 2^7 and 6223 = T(93) + T(56) + 2^8.


MATHEMATICA

tab = Table[1, {i, 30000}]; T[n_] := (n + n^2)/2; Do[n=T[i]+T[j]+2^k; If[1<=n<=30000, tab[[n]]=0], {i, 0, 244}, {j, 0, i}, {k, 0, 14}]; Position[tab, 1] // Flatten


CROSSREFS

Cf. A112625.
Sequence in context: A172731 A230733 A293355 * A232390 A092726 A291422
Adjacent sequences: A112662 A112663 A112664 * A112666 A112667 A112668


KEYWORD

nonn


AUTHOR

Giovanni Resta, Jan 12 2006


STATUS

approved



