A131197 Numbers n such that 1 - S(n) = 0, where S(n) = (S(n-1) + A000040(n))*(-1)^n; S(0)=0, n=>1.

2, 4, 6, 8, 12, 14, 190, 194, 306, 308, 462, 464, 472, 474, 476, 478, 490, 1884, 1890, 1938, 23636, 23656, 23850, 25226, 25834, 25984, 26642, 26650, 26924, 26998, 27000, 311922, 313880, 313946, 331676, 331762, 331782, 332676, 377078, 377518, 377666

Offset

1,1

Comments

The terms are equal to A130642 for n/2 odd (100 terms) and to A130643 for n/2 even (86 terms).

Links

Table of n, a(n) for n=1..41.

Example

S(11)=(..((((0+2)*-1)+3)*1)+5)*-1)+7)*1)+11)*- 1)+13)*1)+...+29)*1)+31)*-1 = -36, 1 - S(12)=1 - (-36 + 37)*1 = 0, hence 12 is a term.
S(13)=(..((((0+2)*-1)+3)*1)+5)*-1)+7)*1)+11)*- 1)+13)*1)+...+37)*1)+41)*-1 = -42, 1 - S(14)=1 - (-42 + 43)*1 = 0, hence 14 is a term.

Mathematica

S=0; a=0; Do[S=(S+Prime[n])*(-1)^n; If[1-S==0, a++; Print[a, " ", n]], {n, 1, 10^8, 1}]

Crossrefs

Cf. A130642, A130643, A008347, A066033, A000040.

Sequence in context: A057220 A294847 A082742 * A078327 A214415 A094109

Adjacent sequences: A131194 A131195 A131196 * A131198 A131199 A131200

Keyword

nonn

Author

Manuel Valdivia, Sep 26 2007

Status

approved