1+21+31+41+51+61+71+81+…1−21+31−41+51−61+71−81+…1+31+51+71+91+111+131+151+…1−31+51−71+91−111+131−151+…1+21+41+81+161+321+641+1281+…1−21+41−81+161−321+641−1281+…1+221+321+421+521+621+721+821+…1−221+321−421+521−621+721−821+…1+2!1+3!1+4!1+5!1+6!1+7!1+8!1+…1−2!1+3!1−4!1+5!1−6!1+7!1−8!1+…1+3!1+5!1+7!1+9!1+11!1+13!1+15!1+…1−3!1+5!1−7!1+9!1−11!1+13!1−15!1+…1+2!1+4!1+6!1+8!1+10!1+12!1+14!1+…1−2!1+4!1−6!1+8!1−10!1+12!1−14!1+…1+2+3+4+5+6+7+8+…1−2+3−4+5−6+7−8+…=∞=ln2=∞=4π=2=32=6π2=12π2=e−1=1−e1=sinh1=sin1=cosh1=cos1=12−1=41
Source: blackpenredpen
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Really cool! @Adhiraj Dutta
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Glad you liked it @Yajat Shamji
If you sourced BlackpenRedPen, he mentions that the second-last series has value 8−1 and not 12−1, although there can be many more values according to algebraic manipulations. Afterall ∞=∞+1
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I used Ramanujan's summation.